The other answer is great, but I'd like to add that sometimes when you join, you have the option to set up a fitness assessment. The Y does this for free, I think, and they'll usually give you a workout routine that you can follow, with periodic follow-ups. For some extra $$$, you can work with a trainer.
I still have trouble with the weight machines. I had a routine once with specific machines/weights/reps, but that was set up for me after an assessment, and will vary from person to person. I do stick with the hour plan they gave me of 5 minute warm up, 25 minutes of cardio, weight training, then 5 minute cool down.
Set up a session or two with a trainer. If you're on your own afterward, at least you'll know what you're doing.
I still have trouble with the weight machines. I had a routine once with specific machines/weights/reps, but that was set up for me after an assessment, and will vary from person to person. I do stick with the hour plan they gave me of 5 minute warm up, 25 minutes of cardio, weight training, then 5 minute cool down.
Set up a session or two with a trainer. If you're on your own afterward, at least you'll know what you're doing.