A search engine....
There are literally a million threads out there for you to read research and consider.
This question "what should I do first/now?" comes up quite often. Read, research and read some more before jumping right in, not knowing what you're doing and hopefully keep you from wasting money, buying the wrong parts, then getting in over your head and having to sell the half done, hacked up "project".
The old saying, "Measure twice, cut once..." applies.
Since you may not know much about the car, get it running as best as possible in its current stage. A basic tune-up is in order.
Replace:
-Distributor cap and rotor
-Spark plugs & wires
-All filters (air, fuel, oil)
Fix anything broken, replace and maintain EVERYTHING as much as possible, spark plugs, brakes, bushings, belts, bearings, ball joints, & fluids. Replacing what needs to be maintained gives you a certain point of reference of what exactly has now been done and shouldn't have to be worried about for a while, instead of guessing or waiting for something to break unexpectedly. It also gets you to know and understand various parts of the car, knowledge that will help you for the rest of your life.
Get used to the way it drives, the way it handles, the way it performs... after you get used to it, then go for something bigger, IE; engine swap, rebuild, turbo, etc.
Be patient and start reading, searching, planning and saving for whatever project you come up with. Don't cut corners or cheap out. Most importantly, there is a lot of false information running around on the World wide web, be careful and do lots of searches to compare answers.