Keyword domains like "makemoneyonline.com" are really great for SEO as they would rank you good for keywords associated with the domain easily but the sad part is that all good keywords are already taken. Good luck if you can find anything available
Rely less on using the domain for SEO. Use it more for making it memorable, catchy, and useful to your visitors so they'll want to return.
a)keywords in domain but do remember come with quality content and good use of the keywords onsite. b)use friendly domain extension like .com to target global and country domain extension to target specific country c) short, not spammy and easy to remember. d) domain which have high PR and lot of backlinks
Of course, there should keyword in the domain related to your business, apart from this, it shouldn't be too long, try to get top tlds like .com, .net, .org etc.