Is it better to use my-domain.com instead of mydomain.com? How about when its 2 dashes like my-first-domain.com or would it be better to just use myfirstdomain.com? Thanks In advance for your advice.
The dashes don't hurt as long as they don't appear smarmy to the user. I won't visit a site like i-own-this-website-here.com but I will visit Free-Marketing.com Too many dashes I think scares the user. But I do not thing the SE's care.
I personally dislike them with the '-' but they can do no harm. And when searching in for example Google, it counts as a space not a '-'
If you're talking about just the value of the domain, then mydomain is better than my-domain. But for SEO, I'm not sure there's that much difference. (You could probably purchase my-domain a lot cheaper, of course.)
No difference in terms of SEO -- but to make money you still need to have domain suited for human users. And-domains-with-too-many-hyphens-look-too-scammy.info
i would prefer the domain without "-" use it only when the doamin you want is not available and dont use it more than once if possible. (easier to remember)