1. Do not just jump right in. Don’t start lifting anything you struggle with. Don’t even touch the weights right away. Work on cardio, push ups, sit ups, etc.
  2. A personal advice is to get a trainer if you can afford it and get a trainer who’s been doing it for a long time. Don’t get some young guy or girl who’s fit. Get an older person who’s experienced the ways of working out and knows what they’re talking about.
  3. People don’t compare bodies: Only a**holes with no lives do this. We don’t need to show off because there’s always a stronger mountain that we need to climb around the corner.
  4. Start with 45min to 1 hour every other day. Try to keep busy while you’re there by going from one exercise to the next quickly. It’s really worth it to have someone first take an hour with you to make sure you understand the basics of ‘good form’ and set you up with good habits. 
  5. PLEASE RERACK THE WEIGHTS: After you are done, please put the weights back to zero or take them off. It’s not your house! It’s everyone’s. So clean up after yourself.
  6. Again, don’t compare yourself with other people. Ask for help if you need it. Proper form. Even things as simple as push-ups should be done correctly. Don’t over do it. If you’re tired or it’s getting too hard to do another rep wait and try again if it’s still too hard, you’re probably done. This is hard to learn though and only you can make that call.
  7. Start slow. Learn what your maxes are and don’t over do it. Focus on form rather than weight. Find what lifts work for you. Every body is different so pick and choose advice that’s given to you. More sets and less reps for strength. Less sets and more reps for definition.
  8. Just know that no one is looking at you and judging you because everyone is so concerned with themselves.

Things to keep in mind – When you start, do what you can. There are different methods of training that all depend on your own personal goals, so figure out what it is you’re trying to do, and do a little research to find the most efficient way to get there. 
You don’t need to waste $250 on 3 trainer sessions when you could go on and figure out what to do and see videos on how to do the moves correctly for free. You’re not gonna get there overnight so be patient and don’t quit, and you’re not gonna get anywhere close to your goals if you don’t eat properly.
Many see the greatest gains by doing five sets, and for each set do 12,10,8,6,4 reps. Increasing the weight as reps decrease. On the 4 rep set I increase the weight by 5 lbs. Each week. 
After about six weeks take a break and then change your routine up. If not your body gets used to the progressive overload of a muscle being challenged a certain way and you stop seeing progress. 
For example Monday being chest day. For six weeks on that day I do flat bench press. Dumbbell flys, and weighted dips. Take a week off and then do inclined bench, cable crossovers, and decline bench.