Well, I don't think I could properly school anyone as to the craft...after all, it took me thousands of hours to get there. I can offer tips though, such as NEVER get a belt-driven turntable...only quartz-locked magnetic drive (and be careful when removing the platter and exposing the magnets; you'll never get iron filings off of them!)

As far as mixers go, that's less important but being able to switch between different modes of cueing is a huge boon, as well as being able to adjust visual monitoring as well. What I mean by that is that it's nice to be able to see both programs as well as the "house" or master mix without having to explicitly listen to them via your cue mix...and it's nice being able to dial in any amount of both "sides" of the mix in addition to listening to the master output at any given time. (I was never a fan of "listen with one ear" method when i could use my mixer's cueing features properly to get a much better result.)

One more thing about mixers (I swear by the Rane TTM series) is that you need to think about whether or not you'd want to add CD players or samplers, etc. later on. If you're going to drop $850 on a mixer, it better accommodate your setup. I ended up with 2 turntables, 2 CDJs, a phrase sampler, a guitar + guitar synthesizer, and a number of different keyboards (mostly sold off now...)

I started with probably between 30 and 50 records at first, and quickly realized that it wasn't enough. Over the years I'd spend a few tens of thousands of dollars to build a decent collection...(even hundreds of jazz records.)

Oh, and if someone spills their beer on your decks at a party...KICK THEIR MOTHER FUCKING ASS!!!