Well, this can be a pretty deep question!
Do you have an idea what turntable you're looking to buy? The manual will give you the basic rundown on what's necessary to set up your turntable correctly (like balancing the tonearm, etc.), and the cartridge you buy will let you know what weights you should use. You'll also want to set it up on a nice stand or piece of furniture that doesn't shake or move at all, and use a bubble level to make sure the platter of the turntable is perfectly level. This is kind of the basic stuff.
For what kind of cartridge/needles you should buy, it depends on what you plan on doing (mixing/play back only), and what you're looking to spend. I'd check out some reviews if you're on the fence, but make sure you buy a turntable that allows you to swap them out.
If you want to delve further, I'm sure there's plenty of guides online how to properly set up a turntable so you might even want to google around or check out some youtube vids. Since it's new to you, it's worth researching that's for sure! It's not too hard, so have fun with it!