The best thing you can do is research. You can find out anything you need to know in this forum, and if you can't find it then make a post and I bet you someone will be able to answer you.
Now you should decide what you want to do with your car and come up with a plan. Based on other people's experience with different combinations of parts put together the setup you think you will be happy with. Don't be like me - when I got my s13 I thought I would rather have a nice looking car than a fast one, so I spent about $4,000 on body work. Now looking back I see I could have a damn fast car for 4 grand, and Im finally getting around to building a KA.
The FAQ section will answer a lot of questions you have:
http://240sx.org/faq/
Have fun.