I have a question about bench press and avoiding injury.

I'm a 49 year old, 170 lbs, man. I don't heal as fast anymore. I've experienced small muscle strains turn into serious injuries by not paying close enough attention to them. So, recently I was doing the bench press. I felt shoulder pain on the second set. I stopped and later googled bench pressing and injuries.
My normal practice is to bench press a weight 12 times or reps for three sets. When I can do that for a month or more, I increase the weight. I had recently increased the weight to 130 lbs. At this point I could do 12 on the first rep, 9 on the second, and 7 on the third.
One of the sites I read from the web said doing 10 or 12 reps and three sets was to many reps for the muscles involved while doing the bench press. It recommended doing 5 reps and 5 sets. It said only to do 8 max. When you can do 6 reps go up on the weight 6 to 10 lbs. Any opinions about this, or advice about how to avoid muscle strain. My form is good by the way.

I don't really think you can avoid it entirely. But 12 reps sounds a bit like overdoing it for my taste at least. I'd stick to 8-10. Also, everyone says their form is good. I'd go back to the basics if you're continually getting injured.