One thing I learned as an owner of an event company is to pay for the venue FIRST. You should not have to depend on booth sales to get the venue paid. You should already have a budget set for each event (money before booth sales) and your marketing budget should be 15%-20% of that and the cost of venue should be included.
That way you as the planner doesn’t feel an unnecessary strain, you wont have to badger vendors for sales or sell too cheap to get vendors. If you do not do your do diligence as the host and you have to cancel an event it will be detrimental in so many ways it would take to long to go through the list.
#1 thing for vendors booking an event at a hotel is if your fee isn’t at minimum $100 then you need to do some research.