For the painting I have done in as much of a controlled environment that I can provide, I have always used the negative pressure method where Fans draw the air in the booth out. After a lot of reading I want to go positive pressure, my concern is this booth is being made of framed wood & plastic and the floor being watered down. If I have a fair amount of leaks with this method still work? I like the idea of pushing everything away than sucking debris in. Any experience would be appreciated.

The trick is to keep the exhaust opening just slightly smaller than the intake so only a small amount of positive pressure is in the booth.
You don't want the air circulating too much.
Ideally, if you can control the exhaust opening size, start with it wide open and then slowing close it down until the plastic sheet pushes out slightly and stays there.