How do you build your car

Step one: get car. Step two: fall in love with car. Step three: build it your way!
Really, man, it's your car. It's your blood, sweat, and tears. It's your money. What do you want out of it? Bigger stereo? Bigger tires and wheels? More horse? Better brakes and suspension? You'll be driving it. Why not make it something you're going to be happy with? Nine times out of ten, unless it's a high dollar Hemi, A12, Ramcharger 426, S/S Plymouth, Winged Warrior, etc car, if you put money into it as an "investment" you're going to take a hit. So the whole "investment" argument is a wash.
Besides, you're still young. Those cars will be in the future. For the now, why not have fun with it?