I can give pointers for inspiration.
There are many ways to go about having inspiration hit for an ad piece. If the event is yours, the terms are yours - well then - you can now do whatever you want. Great power.
But it can seem like staring at a blank canvas. That stops a lot of would be artists - the blank white.
It's like a death stare. So if the image isn't already in your mind, borrow one and twist one.
Forget disc golf flyers. Go elsewhere for inspiration. Google image search is your friend.
Maybe start with style : pick a style or era to work with. Art Deco, Nouveau, minimalist, mechanical, 60s psychedelic, vintage travel, hot rod culture, whatever. Browse say... WW1 propaganda posters, or whatever jumps into your mind. re browse the disc golf throughout history thread, or the DG propaganda thread.
If that doesn't kick something into your head, then go to gig posters .com and browse concert posters. Tons of them on there. Concert posters are unique in that they can be completely random, but still work. Crazy stuff.
You get the point. Flyers don't have to be a silhouette of a dude throwing a disc into a clip art basket. If your graphics are not overtly disc golf - have the words Disc Golf Event, or Disc Golf Tournament featured more prominantly to compensate, say like on the top header. (if your posting it on the cork board at a local grocery store or the like)
Now to my other strong comments about event posters/flyers. The functional side and the psychological.
How you present the event will shape your attenders focus. You get what you ask for. If you highlight payout tables, and have the flyer look like a betting sheet - and do it regularly that way - all things equal you will get players focused on those features. Or you'll train them that way. If you have graphics off putting to females, juniors, family friendly demographics then don't be surprised when you don't attract them. The reverse is also true. Decide if the sheet itself has to have all the information on it, or just the enticing part with enough to get someone to check out a website reference or online sign ups, etc.
Or make one for general attraction with info links, and another small form that can print small that can be handouts and can be jam packed with details and be a 1/4 page "working flier" - ones you can have in your DG bag and pass out when you meet people. Graphics printed as a 4x6 photo are super economical, have great color and people tend to keep things printed like photos, since it feels wrong to throw them away - they tend to stay in players bags or go on their refrigerators. Most won't think twice to throw away a 8x11 copy toner paper.
Best of luck - make it fun, if you cant impress, then make them smirk or smile, make it colorful, and the people will come.
