How to get people on your server

I have a Jailbreak server myself. I also have a lot of friends who play the gamemode. I give my friends "nicknames" on who enjoys populating the server (<5 people) who likes the start up games and who only plays when theres a legit game going on. Dont just spam invites to people though, send a semi personalized message to them. My favourite is:

Heya (persons name/my personal nickname for them) JB is doing pretty good right now, you fancy joining for a couple rounds?

orr

Hey (^^) I see you only have around (how ever minutes) till your next rank - you wanna join now whilst theres people in to rnak up??

I also have stuff in the server that encourages people to come in. I have the daily achievements in Pointshop 2 - so they get 10,20,30,40,50 points for joining each day. then on the 6th day joining, they get a point booster.

I am also adding new stuff and informing people in the steam group. There is a reward for joining the steam group - then they get informed of what I have added in.

Engage when players join. Add things to entice them to come back. Make it fun to play. Listen when they tell you something is buggy or needs changing.