One of the main reasons I found tanking alluring to me was the prospect of being the natural leader of any dungeon run. As the leader, it's your role to set the pace of the run, and to somewhat know how the dungeon is run. One of the perks of playing a tank is the non-existent queue times, so use it to your advantage - run as many dungeons as you can, and get free tanking gear along the way. The Cavalry set from Brayflox is a good set of tanking gear you can aim for. I did the occasional FATE grinding for a few levels, but 35 or so, out of 50 of my GLD/PLD levels were gained purely by running dungeons. As a person who enjoys raiding, I gain more fun running dungeons.
A few more tips: use your AoE aggro skill (whether it's Flash or Overpower) from time to time. The healer generates group aggro every time they heal you, and if you don't continue holding aggro on mobs that your team are not targeting, the healer's healing aggro will eventually overtake yours. Also, upgrade your weapon as you can. If you haven't gotten a weapon for a fairly long time, consider getting a more updated green weapon from your Grand Company. Your weapon's damage dictates your aggro. On lower level dungeons it's not as important, since you always get level sync'ed, so higher level weapons have their stats readjusted for that level too, but this will become more apparent at higher levels - specifically once you hit 50. Mark your targets, so that DPS knows which targets to focus on - if they choose to ignore the marking, I'd let them face the consequences (depending on how nice you are - sometimes I'd try to pull aggro off them and back to me), but if they do it repeatedly, I'd rather let them realize the folly of their errors. They will eventually follow the marking to stay alive, and if they try to talk back otherwise, tell them to follow the markings - at least you have done your job.
Don't let the prospect of bad tanking experiences pull you down. Sometimes you'll get bad teammates who don't know their roles, sometimes you'll have a bad day. All you really need to do more is practice more (ie. running more dungeons). I always try and challenge myself by ensuring that throughout the entire run, I do not lose aggro of even one mob. As you keep pushing yourself, you'll get there one day too.
