Before 4.0 Ive always had an idea on how to tank from past experiences in BC. In BC, at max level I was a resto druid that respecced every once in a while to feral to farm mats and stuff. It’s funny because at the time I had no idea how to dps as a kitty but I knew how to hold single target aggro in bear form. I never tanked any 5 mans but I remember tanking some of the high level elites for dailies and high level quest chains.
In Wrath when I first decided to officially make my secondary spec feral, I put in a lot of time researching how to play correctly and perform the best I could with my toon. I soon became a pretty decent feral dps after spending much time on the target dummy and I also messed around a little with tanking some lower level instances for guildies. When 4.0 launched and the new talent trees were implemented, I found it easier to pick a few of the tanking talents while speccing for feral dps primarily.