Vanilla, and I'm an MMO virgin. Rolled a pally. Ignorant of add-ons or helpful websites; Thottbot, Wowhead, Elitist Jerks, etc. Got to around lvl 55, joined a pug for Scholo as a healer. Talents scattered across all 3 trees into what sounded fun/cool to play. First trash pull and I cast Holy Light on the tank, who dies, because HL was on a long cast time. So we re-enter and try again, same results. I get kicked. No chat, no whispers, nothing. Just...kicked out. I felt miserable. Worst. feeling. ever.
I loved the game, so continued, albeit without joining random groups. Got in a guild, learned from some very good players about using FoL as well as how to downrank. Challenged myself to become greatest dress wearing paladin in WoW, and by the time TBC and Kara rolled around, I could keep the entire raid (including pets; yes, they took damage) alive w/no worry about mana thanks to MP5.
That community support is probably what cemented WoW as my game of choice for many years. Shoutout to Eternal Force, a guild on Ysera, and to Sarcy, the paladin who first taught me how to heal.