What will I need to get for a good car stereo?

I could go into a long lecture on how wattage and sensitivity affects subs/speakers, but its long and confusing so I'll keep it simple. channels are the outputs for speakers. a channel is constructed of a negative and positive outputs for speakers. here is my best advice 1st off, go with a good brand and stick with it, i only run memphis audio products in my cars because thats what i started out on and i know its reliable.also remember there are reasons why when you hear car audio the first things to mind are jl, alpine, memphis car audio, kicker, ect.. its because theyve proved themselves to be good and you can never really go wrong buying their product. you have so many options as far as running amps so i know how it can get confusing, but its all on your preference and what you want to spend. First option is simple, go with a monoblock amp for your subs (monoblock has one channel), and a 4 channel for your speakers to run off of. Your next option could be a 4 channel only, 2 of the channels to run subs off of, and 2 channels to run front speakers off of, and use the head unit to run the rear speakers. next option would to go with a 5 channel amp, which so far i have only seen one quality 5 channel amp which is the memphis audio "belle" and "baby belle". this will give you 1 channel for subs, and 4 for speakers, its like a 4 channel and a monoblock built in to one. the price of one seems expensive, but its 2 amps in one and a very well built amp. wattage does typically seem to matter to most but sensitivity is also needed to take into consideration.sensitivity is the amount of "sound" that speaker will put out on 1w. so lets say you have a sub that can handle 700 watts and has a sensitivity rating of 50db, then you have a speaker that can only handle 500w with a sensitivty rating of 99db. the 500w sub will be louder because it will be a more efficient sub and almost all of the wattage inputted into the sub will be turned into sound. your best option as of now is find a highly rated audio shop in your area and talk prices and options with them. i can type to you all night about setups and options, but a local shop can point you into the right direction and give you the best equipment available in your budget.