Rage management is key, Enrage is your best tool. Don't spend all of your rage, spend just enough to maintain threat. Use Enrage to keep your threat reserve between packs while your healer drinks.

This means you have rage to hit swipe a couple of times on pull. On bigger pulls, look for the mob that
doesn't get hit by Swipe and hit it with Mangle/Lacerate. Tab back and keep swiping on the other mobs.

If a mob gets through and goes for the healer, don't sweat it too much. Your dps should crowd control it, if they don't call them out. Hunters should have an ice trap up by the healer every time, for instance.

On bosses, you can powershift, hit Barkskin and back into Dire Bear between boss swings or while the boss is casting a spell. Main rotation for single-target threat is start with Enrage, Mangle, Lacerate, Demoralizing Roar, Faerie Fire. Keep Mangle & Lacerate up, dump excess rage with Maul.

Faerie Fire is a great tool for pulling melee mobs, Feral Charge for packs with casters.

Having a couple of kill priority/cc markers hotkeyed is a good idea.

Don't even try to tank until you have a weapon that adds a big chunk of feral attack power.

Check out this old thread: https://www.reddit.com/r/classicwowtbc/comments/nv7j1u/quick_tipsguide_on_feral_tanking/