There are some great web sites and youtube pages for this....I strongly advise watching them now and then for new ideas and new motivation.
Best advice I can give is change up your routine regularly.
By basic routine right now: M-W-F Chest, Biceps and Shoulders.
Start with normal corkscrew curls (Three sets of 12)
Then I go to a cable machine and do three sets of 12 rotating between each of low, middle and high cable pulls (Face away from machine and drag cable across your body) this works each pectoral muscle separately.
Then Hammer curl rotated with Shoulder shrugs
Then machine bench press rotated with military press.
Finish with crossbody curls rotated with roman chair leg lifts (100 total)
Finish with 150 sit ups (vary style every day)
T-Th-Sat Is tricep and back.....This has been long enough but you get the idea.
Good luck, hope this was some help and be aware there are many super smart people who think my routine is lower quality. Here is all I know to be true PICK ONE AND DO IT! that is the only great routine....doing one! Have fun bro and welcome to 50+