Most people who do a search for a server filter it by those that have players. I believe that by having at least one 'player' in the server, even without boosting, you will have more people joining the server. With that being said, I'd like to suggest a couple of ideas.
What I would like to first recommend is getting HLTV so there is always "someone" sitting in the server. Your servers will never show as 0/100 or 0/20, etc. It will help allow PVP to be a part of a filter that most likely would have removed us otherwise.
My second suggestion is, IF you choose to get HLTV, to rename HLTV to something with a female name. For example: HollyLovesToVacation Obviously it is an anacronym for HLTV, but you get the point. By having a female name as a player in the server, you'll at least have players popping in for a moment which may lead them to adding the server to their favorites.
Just food for thought. I have other ideas too, but I have to get to work! 😁