When I turn the heat on I get slightly warm

Air but nowhere near as hot as it should be. A/c and defrost work great. Heat puts out slightly warm air but not anywhere near as hot as it should be. A/c works great. Defrost works great. No strange noises. Want to try any and everything I can before giving in and taking it to a shop.

I don't want them to get over on me bc I'm a female in late twenties having to do these things myself. So please advise me on the possibilities and if possible an idea of how to do any suggestions. Thanks so very much!
Mel