Two things I did when I started:

1. I developed a focus of what I wanted to collect and stayed true to it.

2. I vowed to not fund my addiction with family finances.

I bought and flipped pumps, air meters, and signs. If I would have kept everything I bought there would not be room enough for me to store it ... and I let some VERY nice and rare items pass through my hands because I kept my eye on the goal.

I also wrenched on the side for extra cash to take to swap meets and ebay purchases.

Also ... as a side note ... be content with what you have. I don't have the best collection in the world ... but I'm content with what I have ... I don't even allow myself to get into the comparison game.