Is there a way to make sure certain sites don't appear on a Google search?

Definitely the minus is good. Additionally, a plus requires a word or phrase to be present in the result.

Also, put quotes around an exact phrase that you want (or don't want) like "magic mike"

magic mike
returns pages with magic or mike or what google thinks you want

+magic mike
pages must have magic and should have mike

+magic +mike
pages must have both words but they may not be together

"magic mike"
pages have both words and together or what google thinks you want

+"magic mike"
must have the phrase

-magic mike
pages must not have magic but should have mike

magic -mike
the reverse

-"magic mike" +movie
pages must have movie but not that movie

etc.

It doesn't always do exactly what you want and often you have to keep adding minus words/phrases.

site:similarworlds.com boobies
only searches pages on SW

filetype:pdf boobies
only searches for pdf files with boobies in name (or containing the word, I believe)

I'd love to know if there is. I'm sick of all the pintrest results I can't see because I don't have an account.

Enter your search term and then -dailymail or anything you want excluded put behind the minus sign, no space

I think putting a minus in front of the site works.