Updated: Sep 1
It's already been talked about a lot on the interwebs, but I thought I'd post some basic setup steps for hooking your turntable up to your receiver or amplifier. It is fairly easy.
Make sure you have your turntable and receiver/amplifier powered off. Your turntable should have a pair of RCA cables already integrated into the plinth (base of the turntable). Red is the right channel and white is the left. Some receivers/amplifiers do not label them on the back panel so just know that usually the bottom is the right channel.
There is usually a 3rd cable or wire with a u-shaped plug on the end. That is the ground cable that grounds the turntable to the receiver/amplifier. Some turntables ground themselves to the receiver/amplifier via the RCA jacks, but the vast majority of vintage turntables will have a dedicated ground cable. This attaches to the GND, or, ground post on the back. What if you don't hook up the ground cable? HUMMMMMMMMMMMMMMM. Yep, you'll get a nasty hum in your speakers. So, make sure it is secured to the back ground post.
Never hook anything except a turntable into the PHONO plug. Conversely, a turntable can ONLY be hooked into the PHONO hookups as that will have the RIAA phono equalization. A turntable will not function on AUX or TAPE.