Sling? You have one or need one? It's like a holster for a pistol. You need one so test a few out. See what others are using and buy what you like.

Are you shooting more than 300 yards? Yes, you probably want some magnification. No, you may want a red dot, but you would be just as well served to shoot irons.

Magazines? No questions here. Dollar cost average (buy what you can afford regularly) PMAGs in the colors of your choice. You can't have enough. They make great stocking stuffers or trade fodder when you think you have enough.

Stock up on ammunition. This should probably be first, but it seems so obvious it gets overlooked.

Shoot with a bunch of people and you will pick up ideas on what you want based on the kind of shooting you like.

Get to know the local shops. Go to Bear, Jensens, Bowers is great if you get to Denver. Keep an eye out for stuff here on the board. Your money will go quickly.

Be safe.