What to focus on?

Hey everyone! I’m new to FB (got recommended by a friend) and wanted to get some tips from the community on where to start off around here. I guess I should list my own facts first right? I’m a 21 year old female, 5’ 10 in height, weighing around 240lbs. I’ve struggled with weight problems my entire life due to health problems I had when I was very young. I want to both look and feel healthier, and stave off any future health problems (especially the ones that run in my family like diabetes and hypertension). I’ve been very on and off with workouts in the past, but I really want to make it into more of a lifestyle. I also just want to gain more muscle and get rid of the excessive fat on my body. I have a rather slow metabolism, but I also don’t want to have to cut myself off completely from eating and fall back into very destructive eating habits. Has anyone else been in a similar situation and have any tips or ideas on how to start this lifestyle change, what workouts to focus on, nutrition tips? Anything helps really!