It can be as simple or as complicated as you need it to be.
For my first startup we have a few board members, compensation was .5 to 1% equity for monthly meetings vested at 1 year.
They are advisors and as such you should ask them what they expect from you, you from them and provide a framework of the future together - let them know what to expect - don't waste their time and only bring them in for meetings when you are absolutely confused in your immediate path or long term goals and have them provide feedback & their network