Finding a good gym is the most important decision in martial arts. ATT in Coconut Creek, Florida is the gold standard. Amanda Nunes and Kayla Harrison trained there. Jackson-Wink in Albuquerque produced Holly Holm's legendary head kick. Team Oyama in LA is Valentina Shevchenko's home. Elevation Fight Team in Denver trained Rose Namajunas. Fortis MMA in Dallas is one of the fastest-growing.
When choosing any gym, look for: clean mats, women's classes, at least one female coach, a fundamentals program, and a free trial class. You don't need to be in shape to start. You get in shape BY training.