That can be answered a few different ways as I'm sure everyone will have a different opinion. I will answer you directly as I can without giving legal advice. But first, if you are going to flip houses you need to be all in as Arizona is a competitive market. Therefore, education FIRST to get the fundamentals and learn the real estate language. When you are investing your time, actively marketing and pursuing leads, you will NEED to know what steps it takes to convert the leads into deals and paydays.
Now, with that said let me answer your question. You can do these several different ways. However, I like to operate and have a level of protection by using entities such as C-Corporation, S-Corporation, LLC, Etc. I also use Trusts along with an LLC on my long term holds. You could do things in your name or set up a Sole proprietorship with a DBA, but that would be a choice you need to make. The LLC has substantial advantages for flipping, but again that's my opinion.
Best advice do your homework and learn as much as you can, be a human sponge and soak up every ounce of knowledge you can. Then work hard generating leads and getting that first payday. After that it all becomes real. Fail and get back up but keep moving; it's worth it. (Really worth it!) So regarding the LLC there a place in Tempe called "Why Pay a Lawyer?" $385 they will do everything to set you up when you are ready.
Hope that helps and good luck!