If you’re looking for firmer erections, you may want to look into epimedium herb extract - the active ingredient being icariin. You can find it in any major super market, probably labeled as Horny Goat Weed.
The stuff WORKS in my experience. It increases nitric oxide levels in your tissue, allowing way more blood flow. I heard this was actually one of the active ingredients in those Enzyte capsules and is similar to how Viagra works (don’t quote me there).
Anyway, I’m only 22, and I decided to play with the stuff to get extremely riled up with my girl. Results? Totally. Incredibly firm erections, so much that I truly think my dick was at 105% size, literally. My dick would seriously start to drip precum with minimal, if any physical stimulus. Recovery is wicked fast, too. It really was some cool stuff. Sex was noticeably more enjoyable for both of us.
The bottle suggested taking two 500mg capsules a day. This will keep you ready to rock if you keep it up. I question the safety of continued use, since there is little research, so if you try it, go for it a week, then off a week. Or, you can alternatively take 3-4 capsules an hour or so before sex. That seemed to work, too.
As for testosterone, yes you can. I am not into it, yet there are a lot legal (quasi-tested) supplements body builders use. I’d ask around those sorts of forums. Also, certain foods should naturally promote good testosterone levels.