Diving right into a gym membership may not be what is best for your situation. If that's the case, we're laying out 4 tools/tips to get you started on the right path.
10,000 steps per day (if not 10,000) start where you can and build.
My Fitness Pal, start using it to track what you're eating and then start dialing in your nutrition once your tracking consistently
1/2 your body weight in oz of water per day, if you're 150lbs, you need to drink 75oz of water a day, see how you feel, use it as a baseline and go from there
7hrs of sleep a night, once 7 is easy, go for 8 and maybe 9. Do what feels right, start with getting 7hrs and go from there.