haha, start with the big 3 theres a tutorial on how to do it in the electrical section its the cheapest thing to do and a good place to start. you basicly upgrade your electrical by adding larger wires to help your charging system. so the + from your bat. to alternator, ground from the battery, and ground from your engine block. there is a how to is sticky in the electrical section and goes into pretty good detail and has good pics to help. do that first and it will help. basicly for the cost of wires and ring terminals
an alternator may not be necasary yet but i would definitly recomend a second battery in the trunk. look into kinetic, xs power, or deka. you can probably find a used one fairly cheap maybe arond 150 or 200, i would recomend something like a kinetic 1200 or something similar in size. im not that farmiliar with xs