This is less a GM’s tip and more of a Hosting tip; assuming you have a live group and you’re not meeting at a gaming store. Feeding hungry gamers is tricky!
First thing to do if you’re going to take on this challenge is to check for dietary restrictions; allergies, religious restrictions, personal-choice restrictions, medical restrictions. Write everything down. Especially allergies; anaphylactic shock is no joke! This is a list that may get complicated; if you have allergies plus Kosher plus Vegan, you might be better off to suggest potluck, or ordering out.
If, however the list is simple, the easiest thing is to make things that don’t need a lot of prep; throw something in the oven early in the day (ribs tend to be popular). A crock pot full of stew, noodle sauce or chili is also pretty easy. In the summer, you can probably come up with some excuse to break out the grill, if you have one. No one generally objects to barbeque, and there are things you can grill – keep a dedicated section! – for vegans.
Keep snacks around; healthy snacks are usually a good choice; veggies and some kind of creamy dip tend to go over well. Dip can easily be made by mixing herbs and spices into cream cheese, yogurt or sour cream – or mayonnaise. Keep ’em on ice; milk or egg-based raw foods spoil quickly at room temp.
And, of course, there is always the option of ordering out; wherein the only thing everyone has to worry about is waiting for it to show up (everyone already pays in for dinner, right?).