First take three coins and formally consecrate them to Hermes. They should be, if not the same denomination of a similar size and value so as not to skew their statistical probability or your interpretation. As part of the consecration you can decorate them (for instance by inscribing a sigil or blackening out the reverse) or anoint them with chernips or his holy oil.
Pray to Hermes for guidance, state your question as carefully and simply as possible, and then throw the coins, interpreting their fall as follows:
3 heads: Emphatic yes.
2 heads: Yes, but it will require effort and thought.
1 head: You should probably reconsider your plans.
No head: You don’t have a chance in hell.
This system can be used to get answers from Gods and Spirits other than Hermes – indeed, because of its simplicity it can be employed by beings who might have difficulty with systems of greater or more specific symbolism – though you should confirm that they are willing and able to communicate through it first. When doing so I either throw coins that have not been consecrated to Hermes or ask him to act as intermediary and interpreter for the other party. In addition to answering questions this system can be used to corroborate the results you get through other forms of divination or direct oracular messages.