Tips On Leveling Guard?

Just wondering where's the best place to start leveling this skill. I was thinking Mandies in the Tree for a while but don't want them to die too fast that I don't skill up lol. Do you have to be engaged to Guard? I know Abyssea is the best place with Atmas and ***, but my Guard is only 70~ so don't want to start too high.

Guarding is basically skilled the same way for parry. You do need to be engaged in attack mode, but do not need to be attacking the mob to gain guard skills. From what i understand.
Mandies are by far some of the best mobs to skill guarding up on. Trick is not to start on too high level of mob. A good rule of thumb that worked for me is take your guarding skill level and divide that by 3. So @ lvl 70/3 you should be going for mobs roughly lvl 24ish. At that level i went to the Jungles and /dnc. Put all the PDT and Guarding skill +gear you can get. Skill gain food and of course gear if you happen to have scored one. Pull as many mobs as you can to a tunnel. I had maybe 20ish. Try to line up as many as you can along a wall facing you. Target an outside of attack range mob (a ranged attack type of Gob worked for me) and let them just go to work on you. You will be in attack mode but not hitting any of them as they are out of range. Don't use counterstance. I didn't have any adargas hands so I was just was bare handed.
Curing Waltz when needed. Gonna take a few hours to get up past 100 skill because they wont actually hit you very much. Prob a few rounds of pulling from counterattack kills.
Get upper end of 150 to 170 increasing the mob levels until then. Then just do abby its way easier and the mobs will actually hit you.
Thats how I capped my parry and Guarding skillz.