As Darvin said Neutral extractors are ESSENTIAL to a Vasaris economy. Build a decent group of scouts and grab them as you find them, then hold on to them as best you can.
Continuing to milk that subject, there are quite a few ideas on what you can do to better use you scouts as Vasari.
1] As you send them to scout, turn OFF the autocasting on detect mines. It REALLY helps them choose their next planet faster. With mine detecting ON, they tend to lag after every jump. Without it, they quickly select another planet to scout.
2] When you find an Asteroid Belt or any neutral extractors without rebels/pirates, order your scout right between the asteroids, turn off the scouting and leave the capture extractor ability on autocast.
3] If there are rebels/pirates in the gravwell, use shift key to order your scout to move all the way across the gravity well 10 times in a row. Pirate ships won't catch it, it won't get hurt. You have to remember about him though and once a while you have to manually stop that game of tag, order the scout to capture an extractor and once it's done - queue another 10 runs through the gravwell.
4] Always start with at least 3 scouts. You can get as many as 6 or more, even if you don't plan on using them in combat. But you NEED those neutral extractors and you NEED scuots to get them.