Your problem is that you're building too many defenses too early. Try instead to expand quickly and build a strong fleet. A colonizer cap (Akkan Battlecruiser, Progenitor Mothership, Jarrasul Evacuator) is extremely efficient at expanding. Just keep colonizing worlds to get a quick dominance on your foe. Against the AI, LRFs (Javelis LRM, Illuminator Vessel, Kanrak Assailant) are a very good ship to use; build many.

For actual defenses, Repair Bays are easily the best. They're cheap and extremely efficient at keeping a fleet alive. If you have Entrenchment, an upgraded Starbase with repair bays can handle a good-sized fleet. Against pirate raids, the best bet for a defense is a capital ship with a few repair bays. The ship can easily handle any pirate raid, and gives a lot of levels!

What you encountered are the defensive militia that are randomly generated at each planet. They aren't controlled by your AI opponents- they just stay there and attack anything that comes in.

Btw, congrats on getting the game. Any chance you'll be joining us for MP (after you practice up a bit?)

My first impression is that you're not capturing enough planets before you hunker down and start turtling.  If you want $$$, the best way to get them is to capture planets.  It can be very tempting to build expensive structures like trade ports early on, but this doesn't make economic sense until later in the game.  It always depends on the map, but in general you should ensure you have at least 2 planets for every 3 your enemy controls.

The first thing you'll do when a game starts is dispatch scouts.  You need to know the map layout; where is the wealth, how well is it defended by militia, and where is the enemy.  As you start to get the whole picture, you should be formulating your strategy.  Which planets are you going to take, and how are you going to take them?  There are only two reasons to stop capturing neutral planets:  either you need to recall all your units to the fight, or there is literally nothing (accessible...) left to colonize. 

As far as defenses go, your best bet is always with your fleet.  Turrets and hangers are exorbitantly expensive, particularly if you need to buy tactical upgrades to build them.  You will almost always get a cheaper and more effective defense out of your fleet, and it is capable of moving from one planet to another.  The best static defense to support a defensive fleet is always the repair bay.  In fact, a single level 1 capital ship with two repair bays will defeat any pirate raid, even at maximum danger levels. 

Contrary to popular opinion that it's a rush game, this is the first thing a player does in Starcraft: get defenses up at choke points.  Although its pacing is different, Sins is in many ways more aggressive than Starcraft because there is a much greater rivalry for resources in the early game.  In Starcraft, it's very common for most of the expansion sites in a 1v1 to be untouched over the course of the game.  This is untrue in Sins; unless players started very close together it's more likely that virtually every planet will have been colonized before the game's end.

These are called neutral militia.  They inhabit the neutral planets at the start of the game, and must be eliminated if you want to claim their planets as your own.  The number and type of militia depend on the planet.  Asteroids are always very lightly defended, ice and volcanics have low to moderate defenses, and desert and terran planets can be moderate to extreme.  The neutral militia will attack anyone, including enemy AI players. 

You can colonize the planet while militia are present, but any siege frigates in the militia will immediately begin bombing it.  If you kill the siege frigates, you can colonize the planet and then build turrets to kill the remaining militia.  This is a favourite strategy by multiplayer gamer and if well played can defeat any militia force.

I am talking about the repair platforms. If you're TEC or Vasari, they can be researched with only one military lab. Advent takes two labs, but are a bit better with healing. These are especially good defenses, because you can plant two and quickly repair a fleet within a minute.

Those are the planetary miltia, as Darvin said. Militia are always unupgraded TEC ships. With Asteroids, you can kill all of them and colonize. To quickly colonize, clear out all the siege frigates and LRFs, colonize, and built a turret. The turret can usually clear out any remnant militia, and saves an enormous amount of time otherwise killing off their durable ships. If the planet has multiple Kodiak Heavy Cruisers, you might want to build two turrets and a repair bay. Afterwards, scuttling the turrets will give back some of the much-needed resources.

EDIT: Also, you really should look at the Multiplayer replay topic and download some of the replays. It's extremely helpful watching what some of the veteran players do, and can really improve your playing style.

Agreed. You can learn a lot more a lot quicker by watching people who have done it a lot longer than you ever have. Simply because people are WAY better than AIs in this game.

I think that there is a third and fourth: It is not profitable to colonize any more planets (I.E., they all are right next to enemy strongholds, or they are just SO FAR AWAY that the income reduction from distance makes them not worth the time or the development resources, in the long run. But thats rather rare); the planets that are still neutral have absolutely no strategic importance whatsoever.

just a side point, if you are using the Akkan (or any other colonizer capital ship, the Mothership or Jarrasul) you dont need the colony frigate, just make sure to put a point in the colonize ability for the colonizer capital ship

Good advice, SS.  Thanks.

Discovered that as I progressed through the game.  Good point!

I redid the initial 2 player map last nite, actually tweaked the AI down to "easy" & played again taking all the advice here.  I did much better, especially since I was not so concerned with getting a whole garrison of turrets initially.  I turned the pirates off (or so I thought) but there was still a whole system chock-full of 'em.  But they never attacked me.  I have about 80% of the game done.  Will have to take out the pirates & 3 more planets & I think that'll be it.

How long does a average game take?  I thought I was moving along fairly quickly but I'm still at over 3 hours with at least another hour to go.  I'm not complaining mind you...this just adds playability in my opinion.  I'm just curious to know if I'm going too slow or what.

Stay tuned!!

when you got your feet under ya and want more try this mod

https://forums.sinsofasolarempire.com/335474

Side note...I'm starting another game after winning the last one.  Do I have to set up my player' name, pic & colors each time I play? 

Well, could you please elaborate as to how I get passed this? 

Also, I was told by Ryat in another post that to watch replays of games I must find replays made with the version of the game I'm using (v1.181).  Could someone please finish Ryat' post & let me know where I can get replays of games using v1.181?  Thanks

Well, at any rate, as to your general strategy..

I was at one time a player very much like yourself.  In virtually every RTS game I have, I turtle.  Since I started playing sins, I've adopted a new strategy: Expand as quickly as possible before hitting the enemy line.  Once that occurs, entrench said planet and create another fleet to colonize the worlds I missed earlier while I colonize the other border planets with the first fleet, but I never have it go more than two jumps away so that it can return quickly should the border become endangered.  (Later in the game I get phase stabilizers up because I play as Vasari so I can go however far away I want and still return more or less instantly)

My point is, learn to expand quickly.  I originally played as TEC, and they were okay, but I then tried the other races.  As it turns out I expand far faster with the Advent and Vasari than with the TEC (I can't stand the Akkan in any way shape or form, so I never get it).  The result was that thanks to the Progenitor and Jarrasul, I was able to expand fast enough to defeat normal AI's (to begin with I struggled with easy ones).  Then over time I've gotten better and now I can kill unfairs with relative ease..

In the thread, Behind the Times (in the general discussions forum), I explain what I did to defeat a heavily and almost insurmountably defended enemy.  Now, this was done using Entrenchment, but the same principle applies.  If the center of the line won't give, try to flank them.  If that flank won't give, create a second fleet and put pressure on the opposite flank.  This forces them to split their forces (making the first battle easier, and causing some lag before the troops arrive for the second one, allowing you to push a planet or two in before they arrive).  Now, since you have vanilla, entrenching is far harder, but it can still be done.  The point of this is, put pressure on them at all times and don't let them know where you are going to attack.  When you do, be swift and wipe out the colony and begin establishing your own before they arrive.  Once they do, attack the other flank.  Rinse and repeat.

Also, once you decide on a dominant race, tell us so we can give you specific information on it..