I did one of my sexual health research projects on jelquing. It has honest merits.
A beginner "routine" would be something like
10 min warm towel wrap/shower
5-10 min stretch in all directions(pull firmly but not to point of pain)
10 min wet jelqs (look up technique for it, basically an OK sign grip from base of shaft towards head) (never do it dry)
5 min warm towel wrap
Continue for 90 days as conditioning. You may or may not gain on the conditioning routine, but it's necessary before you go into the bigger stuff. Many people do gain within the first 90 days though. I guess you can PM me for more resources, I have a whole bibliography on the stuff.
As a side note, it's not something you can pick up whenever you feel like it, it requires time and dedication. That being said, it has proven efficacy rates.