Start off with proper maintenance of the vehicle and a tune up. Get it to the best running shape it can be. Then clean then crap out of it. Inside and out, and the engine bay.
Research other builds of them same chasis and get ideas for how you want to tune your car. Build a game plan and don't cheap out on parts, make a list and set goals for yourself to attain. As you start to mod take the time to enjoy each one performed and don't be in a rush. Patience is the most valuable tool in building a car and it's more about making quality choices in your tuning for a premium end result.