Please, please, please, do not rush out and buy paint!
It is a big pet peeve of mine that every instructor has a slightly different supply list. I love to study with other people. But I hate having to get new paints that I may never use again. If my husband ever know how many tubes of paint I have purchased over the years, he would kill me. Use what you have! I will paint the majority of any portrait with just a 3-color triad.
What I want you do is have a cool and warm yellow, a cool and warm red, and a cool and warm blue. I have some convenience colors on my palette as well.
Here is a list of paints currently on my palette and some substitutions you can use, if you have them instead.
In my studio, I use a Stephen Quiller palette, which sits on a rolling dental tray. There is a porcelain version of this palette available, but I just use the plastic version. (Maybe one day . . .)
Here's a link to my 2020 supply listIt contains both of the above images.