I am interested in selling my designs/doing some freelance work, but I'm not sure how most designers handle fonts. Do graphic designers make their own fonts? If I already have fonts like Arial and Helvetica on my computer does that mean I can use them in my designs? What do I need to know about font licenses? What are some legal things I should know about fonts? Any advice about this would be greatly appreciated!
Just answering some of your questions.
No, most designers don't create their own fonts. It's plenty of work and there are a lot of existing fonts available. I wouldn't create your own fonts if you're starting as a freelancer because it would probably not generate income (compared to the hours of work). You can use free fonts or buy fonts, and to use them commercially you should check their licenses.
For legal questions you have to do research for the particular font you want to use, or contact the designer. See links in the comments posted by others.
Do research on fonts and when to use which font (serif, sans-serif). Blogs should have a whole other kind of font than a button on a website, because of readability reasons.
Some helpful links: