How to get into cabals:

1. Read the cabal helpfile.
2. Roll a character that the cabal accepts (suitable align/ethos/race/class). This is the important part. If you are something the cabal hates, your chances of being accepted into the cabal is near zero. Also note that orcs cannot join any cabals.
3. Make a role that is suitable for the cabal and live according to the cabal dogma.
4. Pledge to join the cabal as soon as you are able and write a note to the cabal on why you want to join it. After you reach level 15 would be suitable time to pledge for the cabal, although it is possible to do so at level 30 too. 15 is better though.
5. Speak with the mortal leader of the cabal and get an interview to get in.

As for heroing, one simple tactic is to powerrank to hero in groups of three people. It's hard to be specific since I don't know what kills you off early.