Here is the most important protip you will ever hear. Start socializing, be a teamplayer, get into a guild and participate in guild raids.
There is a simple logical reason for this, no matter how much gear your solo/pug farm on your own, it will all be collecting dust and feel pretty worthless unless you are using that gear to play the game constantly and raid.
Decide what spec you want to main and for starters try find a Kara guild (Guild that runs or is trying to run Karazhan/Gruul/Mag on a regular basis).
If you are dedicated, a teamplayer, having fund and making friends in the process then everything else (attunements, rep, gear) will come as a natural results of your activities. Enjoy the full Tbc PvE experience.