I got into stand up through doing open mics. Most of the venues that I performed at in the beginning were not stand up venues. It would be a lot of musicians and then me. Sometimes it went well, sometimes, I was just annoying the audience.
The best way to get into stand up is to find any platform you can and just do it. There is no way to practice stand up, as, due to the crowd, there is no real rhythm that you can set yourself into. You can practice timing, but, the only way to get good at stand up is to do stand up. That's the most beautiful thing about it.
I'd suggest writing about 3 to 5 minutes worth of material, and trying it out anywhere you can. And then keep trying it out anywhere you can. And the take out or fix what doesnt work and write more jokes and do more shows. That's the best advice I can give.