Don't expect to make any money. In fact, be very prepared to make a loss.
Don't expect the locals to care about you or your show.
Do a dry run of your show for a week in Hull, in a room in a friends house. Invite no more than six people so you know what it will be like to perform to your largest audience at the Edinburgh Festival. Try not to have more than 3 or 4 hours sleep each night and only live on expensive junk food. Avoid water at all costs by only drinking alcohol. Dress up in costumes that only your group will find funny and hit the streets of Hull with a bunch of overpriced flyers that have at least two typos.....if any of your quips make someone laugh when they take the flyer out of your hand, do NOT presume you have generated a guaranteed customer for your show.
If at the end of this week long practice you and your friends can still stomach the sight of each other: Good luck, you are now ready to experience the Edinburgh Festival