Thomasthetank

Truthfully it depends on what your goals are. Your age will be a factor, but with the right diet/exercise plan, you will still be ahead of 90% of guys in their twenties at the gym.

If you want to build muscle, 5-10 reps to fail is generally considered a pretty full proof way of getting a good mix of size and strength. I'd go for a 3 day split, as opposed to 5 day, because your body will take longer to heal than a younger man. You have to be careful of injury, without meeting you I can't tell your physical condition. Working to fail might be dangerous. So I would start off just pushing to moderate difficulty and seeing how your body recovers from that. If you think you can handle it, work to failure.

This has got a ton of great information regarding 3 day split ideas.
Bodybuilding.com - What Is The Best 3-Day Split For Muscle Building?

But see what you like. After all, going to the gym needs to be a fun experience for motviation, so if you really hate one lift, don't do it. There's a thousand ways to get to a muscle.

Do you have experience with free weights? If not I'd get a gym buddy or someone to show you the ropes.

I use a mix of free weights and machines, even though the latter is considered the devil by some trainers.

However if size means little to you. Lifting heavy up to 5 reps not to fail should give you pretty awesome results.

Don't fall into the bulking/cutting myth, that's for top tier bodybuilders and as we get older it gets harder to get rid of the fat.

Spend a few weeks as a trial and error period to find out your maintenance weight, be honest and keep a food blog. Then when you're confident of your daily burn number, add 300-500 calories to build muscle. Any more than that and you'll just add fat.

If you're not a regular weight lifter, your first sessions can take a long, long time to recover. Don't be surprised if you ache well over a week. That timespan goes down as you practise, don't be disheartened, everyone goes through it, give your body as much time as you need.