Back in the day we did "back and bi and chest and tri"
Back and biceps one day then chest and triceps the next. Squats will help you immensely, as will lunges.
I would recommend rowing, weight training, medicine ball throwing and the resistance band shoulder exercises, or any other hi rep low weight based workout in this format for maximizing your strength & stamina. You want lean cut long muscle, not bulk.
Those cross weight wire trainers are awesome also, you can do military should presses, lat pulls, tricep pull downs, and Bicep curls.
To get the most from your workouts you will need to eat correctly, rest, and stay focused on your long term goals. Read up on sports nutrition, this will go a LONG way.
Stretching after your workouts is starting to become popular and lot of people swear by it. I think most players here over 40 would agree with me in saying they wish they had the flexibility they had 20 years earlier. Many flaws in rec players like me come from some inability our body has to have a technically sound swing.
For instance, 35 years of skiing has left me knees with some pretty bad ligaments and tendons that send nice little warning pains to my brain whenever I get low for a hard ground stroke or low volley. This causes me to start hitting flat footed a couple hours into a match and can really mess my game up. Would proper stretching have helped? Who the blank knows, but I never once stretched before skiing 5-8 hours. It's just something you don't think of when you are all geared up and ready to go.