First you should make sure it's even usable and doesn't leak. Fill it up 1/3, and put some newspapers or something underneath, wait a couple days, check for leaks. Then fill it up 2/3, waiting a few more days, check for leaks. And finally fill it up all the way, waiting and checking for leaks. If no leaks you're good to go, after a good rinsing of course...
For good filtration you'll want your water to be completely turned over at least 3 times per hour, but I'd aim for 5-7 times. So I'd say you should have a combination of at least 1000gph with your filters. (Even on my 75 gallon I have slightly over 1000gph) Power-heads would be a good addition for overall water movement, which helps with oxidation.
What kind of fish are you going to be keeping?