To ensure that the whole raid can easily do certain basic tasks efficiently, every person on a raid should be able to invis themselves, shrink themselves, and gate. This is trivial for classes who can cast such spells, but even if you can't, there's an easy option: potions and clicky items. You can buy invis potions in the Plane of Knowledge. Gnomes can tinker shrinking devices and shamans can make gate potions.
You will often need to use the above mentioned items more than once on a raid, so make sure you carry enough of them.