At that level, neither you nor the other players have the full skill set required to more tactfully deal with the encounters. Therefore, you can very easily spam your skills and acquire aggro and get yourself into trouble--because the game mechanics are tricky.

Use stoneskin to generate less enmity. Use repose (28, I think), to lock down mobs the tank is not focused on. Black mages should have that skill early on, so if they're not using it--shame on them.

It gets easier around 30, but only if you are paying attention to your heals and using your toolkit. If you spam heals like no tomorrow, then you will run into some problems.