What do I need to know to start a business involving audio equipment?

I am trying to start a business. I am going to provide custom audio solutions to students and fraternities at my college. What are some sites or articles I should look at / read to really feel confident that I can give my customers EXACTLY what they want / need? I welcome personal advice, but sources are really what I’m after.

I need to know anything and everything about:

what types of speakers sound the best
what qualities to look for in speakers/amps
what the true value of speakers/amps are
where to put speakers for the best effect
and anything else that you think will help!

Thank you for your help!