Teach yourself to beatmatch manually, first, regardless of what you get. No visual cues, just your ears and headphones/monitors. After that, teach yourself to mix without any effects, loops, etc etc. This kind of monastic training will prepare you for mixing on virtually any kind of gear. After that, you can start to get crazy with all kinds of digital features, but you’ll still have the base knowledge of how to rock things if you have a bare bones setup.
Considering you’re starting from the ground up, I’d recommend using traktor, for better integration with emerging technology, HID, and built in soundcards. This way, you can mix using a controller/soundcard, a traktor audiobox, or a new CDJ with integrated HID with or without soundcard.
I’d recommend you get a controller/soundcard interface, if you can get a decent computer to go along with it. It’ll have everything a traditional setup will have, but will be way more portable.
Also, if serato is already set up somewhere you’re playing, you can download the proper drivers and use the serato box with traktor, if you’re just using audio outs, and some electronic controller. (doesn’t work with traktor scratch afaik, but again, not an issue if you use a controller)
OR, if SSL is somewhere you’ll be going, you could just download the SSL software for free, use the existing mixer (if serato is already there, then a mixer will be, too), plug into the serato box if there’s other methods of controlling the software. (borrow someone’s needles/timecodes, bring timecode CDs, midi map basic functions to your controller on the fly, but still using the serato box as audio out) The serato interface is dead easy to learn, and even the ‘midi learn’ function is quick enough that I could see mapping on the fly working for basic 2 deck mixing.
Right. I think i’ve rambled enough.
TL;DR?
Go with traktor and a controller/soundcard interface. It will be just fine to learn on if you have digital music, and considering you’ve already paid for traktor software, you have MANY MANY options when it comes to playing on your non-native setup, even with Rane hardware.
Unfortunately, it doesn’t work as well the other way with Serato. Unless you also buy a copy of traktor, you’ll be forever (well, for now at least) tethered to a Rane box. I think that, although it’s not that much of a chore to bring your own box and hook into whatever, it’s not forward thinking enough given the explosion of mixer/player options that are starting to integrate soundcards, MIDI, and HID controls.