I am new to car audio, I'd really appreciate any resources or recommendations on picking a sound system. The car is a 99 Civic LX. Thanks!

main thing is to not look like a ricer with a civic, & thats hard
so u dont want nething like power acoustik or such, they suck & r in every other civic out there (unlike me lol polk & powerbass system in an 07 civic)
if u want QUALITY
i suggest alpine, sometimes jl (very pricey for what u get) POLK, powerbass subs, & kenwood
i actually have a pair of alpine type R speakers for sale that will fit in ur car (u have 6.5'' in the rear right? check at crutchfield.com)
and l have a pair of component MB quart speakers which should fit in ur fron 6.5'' woofer, 1'' tweeter & crossover lol

but ur prolly not in ct & l dont wish to ship em hahaha