If you are in need of a way to advertise
Generally, you want a phrase to be the main focal point on the flyer. This might be the name of whatever is being advertised, or it could be a question or refrain which catches the attention. If you’re going for the latter option, then you might want to think about a phrase which is confusing or alarming in some way (without being offensive, of course). If you do this, people will be much more likely to stop and look, and that is the goal you are trying to achieve here. It is also worth looking at what font you are using. If you are using something that catches the eye more easily, then you are more likely to do what you are trying to do.
You can’t really have a flyer without an image of some kind or another, or ideally a few images. These need to be relevant to what you are trying to promote, and they also need to stand out in a big way. It can be difficult finding appropriate images which don’t cost too much, but using a website for stock photos is a good way to go. These are generally royalty-free images, so you can usually use them freely, and if you are willing to hunt around it shouldn’t take too long to find the ideal image for your project. The right image has a way of completing a flyer, so this is worth looking into.
Focus On Color
Color is a hugely important part of the flyer, and it might even be worth getting to know a little behind the psychology of color. Certain colors evoke certain unconscious reactions in people, and if you want your flyer to make a real impact, you will want to go for colors that both make sense with the theme of that which is being promoted, and have a good effect in terms of trying to sell that thing. This can be tricky, but with a little research and forward-planning, you can integrate your color choices in a way which makes a vast improvement to your flyer. It is worth saying too that you shouldn’t try to go overboard on color. If you are too bold, or use too many in a small space, this can hinder your efforts.