The following are a few tips on how to keep your rugs simple and to make sure rug hooking doesn't become a stressful part of your life.
Try keeping to a small palette of colours when working on a rug, about 3 or 4 works well. You don't want to try to utilize an abundance of colours and force them into working together, as this can become a bit of a nuisance if there's any hiccups that occur while hooking your rug.
Use simple shapes for design inspiration in your rug. Cirlces, squares, rectangles, triangles, stars, all look nice in a rug but aren't too overpowering or difficult to create. Other shapes can sometimes end up looking wonky, or if the shape doesn't work out the way you were expecting, it may add unneeded frustration into a time that should be overall relaxing.
If you're a beginner at rug hooking, you'll want to start out with a manageable project. If you take on an overwhelming challenge right in the beginning, you may become discouraged and give up the craft all together. Completing small projects and getting used to hooking will give you the satisfaction to continue on making rugs in the future. Bigger is not always better!
Don't worry about any rules you've created for yourself or what anyone else told you. You make the rules when you're rug hooking, you're creating the rug for you, and it needs to please you. Taking rules out of the equation will give you the freedom to express yourself and take any expectations off of your shoulders.
Try not to overthink about your rug while you're hooking it, just continue to work towards finishing the mat. You'll feel much better with a completed project in front of you than a half finished rug that you keep unravelling and rehooking! You may not always end up loving the finished result but you'll eventually learn what your likes and dislikes are in the rugs you're creating.
Making your rug complicated is an active choice, keeping the art simple all depends on your mindset about it. Keep it simple and relaxed, leave it as a hobby that you enjoy and whatever you end up creating is fine. Have an open mind and don't be afraid to experiment with different elements of rug hooking!