Maybe you've seen the "kits". All black frames with white mats that make up a perfectly symetrical gallery wall of art or photographs. You could purchase one of those. Especially if you haven't done an art wall before, you may feel "safe" doing that. Nothing wrong with that. There are some very good tutorials online to get you started also.
Some designers have a lot of rules, i.e. use all the same color frames or the same color mats or art in the same color family. Go only horizontal, go only vertical, etc. I've including a few examples of these.
I personally like the organic arrangements that start with minimal planning and have room to grow. Of course you want to consider a few things such as space between each piece and which direction you'll grow in. Starting with a large blank wall is key and it is often easier to start with your large piece in the center. A nice, big wall is necessary so you will have room to add pieces in the future as well as something besides one dimensional art if you choose to put that in your collection.
You gather your art of various styles, shapes and sizes, compile other things you love that you can mount on a wall, and you JUST START!
DON'T BE AFRAID! DON'T WORRY ABOUT HOLES IN THE WALLS! That's what putty and paint are for!
Here's beaucoup of inspiration for you. Enjoy!