So I joined the support staff union at school last year. Our building rep retired and

[Grumpy Old Guy]

1. Have a thick skin!

Think like a lawyer and concentrate on the important issues. Don't let the superfluous stuff get in the way. Know your contract and keep it handy. If it's not in the contract it doesn't exist. Remember that there are usually some reasonable people on both sides of the table, and some not so reasonable. Hard facts and evidence are good things to have during a grievance. Do a lot of listening, and don't expect anyone to thank you. Remember, you are doing the right thing.