Off road or street?
Will you be affiliated with a group, or doing it as a private party?
Will it be non-profit (people don't pay to enter), or will you or the group make profit?
If it's organized (advertised, asking an entry fee, etc), you will need insurance, and you will need to notify the correct government agency and usually need to acquire permits.
Our poker runs always have 7 checkpoints. The worker at the checkpoint has a plastic bucket with a deck of cards inside, the rider reaches in and picks out one card. The worker writes the card (like KH for a King of Hearts) on a tag which has the rider's name on it. Each check point has a worker that does this. When the rider gets to the end point, another worker takes the tag and figures the best hand from the 7 cards.
Another option is to have games at the check points (hit a badmitton birdie, dart board, wheel of fortune, etc), getting a high score at these games can earn the rider extra card draws - makes it more fun.
The logistics of setting up a Poker Run can be tough for a first timer - but it's a great money-making event for a club if it's done right.
You have 5 locations. Each location has a deck of cards (or however many decks you need in order to ensure there is one card at every location for each participating member of your poker run). People drive (or boat) from one location to another gathering one card from each location. At the end of the day (a predetermined set time) everyone meets at a 6th location to determine the best 5 card hands.
There is typically more than one winner so depending on the number of entries you have, you decide how many of the top spots will win something.
There are usually prizes awarded for high hand, low hand, etc.
you get a card at each stop, best hand wins.... it is not a game of skill (unless you count drunk riding as a skill)