What is the etiquette pertaining to inviting people to act as my reference? Thank you very much

First always seek the person’s permission before putting him as a reference.

Always get his correct contact details. If anyone cannot contact the reference on your CV, that is suspicious.

Next always have the courtesy to inform the person of the position you are applying for.

When you change a job again and use him as a reference always have the courtesy of using him as reference again. It is rude not to do so and you wouldn’t want your reference to tell the person doing the reference job “Gosh, I didn’t know she change job again.”