Domains use alphabet and numeric symbols. Periods separate the different parts of a domain. Hypens can be used to separate words. Most other characters (eg...#, %, &) are not permitted.
If you have a purpose or a goal, can you create an acronym, easy to use? Use keywords and target your areas.
The shorter the better! They are easier to remember! In time shorter domains become more valuable.
Search and check out free domain valuation sites, if your interest is in value.
Caution with running words together, you may create gibberish. Hearing and knowing your domain reads differently when letters run together as one word. Write it in your notebook and look at what you wrote, ask someone what it says. You will be surprised what another sees.
Research your domain. Make sure the names are not trademarked or copyrighted. Infringement may cost you a fortune.
A good name may be written several different ways. It can be written originally or with a play on words, or with a number that can mean something. Do you want someone else to purchase the second name that could be yours? Do you want to purchase the 'other name'?
Is your name good? Ask your friends, evaluate your needs and do your research!