This is what I posted in the SO forum regarding jailbreaks population, I felt like it wouldn't hurt to make a post about it since SOs are not the only people that can help. Feel free to post other suggestions about the matter, please be serious about it and don't meme...
"Since I mainly play on JB, I will say what I think has to be done to help the pop for JB.
Getting a consistent population can be done by getting regulars, either new or old players. People dislike to play on an empty server and it's usually not that fun to pop it, but I need all of you that actually care about the server to get on and try to pop it even if it's not that fun, it will for sure pay off in the future. @fps_trucka and some others almost "revived" the server about a month ago (We went from 4k to 2k in server ranking), this was mainly accomplished by popping the server everyday for about 2 weeks. Jailbreak has always had ups and downs regarding the population, but it has always been brought back to life. We can for sure do this again. I will keep pushing out events and popping the server as much as I can, because I care about the server. I can't do all of this alone, I need your help, even if it's just by getting on and playing a few rounds. We have an event on Friday and the skins will be added again, this is a perfect time to get started. Popping the server for about 2 weeks should be enough to get some regulars and new players.
Sorry for being so inspirational lmao.
The second thing that has to be done for people to enjoy playing on the server is the warden problem like @krony mentioned. Please inspire the wardens to come up with some fun games and fun things to do, or take warden yourself and do something fun. If you see a warden doing climb 3 rounds in a row you should tell him to do something else and spice things up abit, instead of leaving the server because you think it's boring."