Well it was a long time ago, but I started off mixing house music with 3-4 different tunes that had a real easy clean start to the tracks and worked from there. Running 1210 mk 2's at the time (i was lucky to get them as my first decks)
I had lots on lots of friend who saw me bang in a track and think " wow that looks easy" give em half hour on the decks and they really found out how hard it was to do if you dont know what you are listening for. I guess its all to do with getting your headphones set right to hear both tunes at the correct level. I am always playing with the headphones volume control.
I went on to run Newmark TT X1 decks, Newmark CDN-88 cd players and a Korg Kaoss mixer. Good times