Thought I'd make a post pointing out problems I see with almost every RP server I've been on.. Everything that follows is obviously my opinion so feel free to disagree, just don't flame me for having it.
What a RP server should have:
A story (either play made or built in)
An interesting setting
Add-ons that fit
A reason to play
What a RP server shouldn't have:
Jets enabled unless it fits with the setting
Default global chat unless it fits with the setting
Irrelevant add-ons
An empty build - a build with no story or things to do (some are beautiful but absolutely empty).
Excessive combat or mats grinding
It should have a story. This means people get to come up with a character to play as, go into the environment, meet other players (maybe some NPCs) and bounce off of each other. That last part is crucial. A lot of RPs have these really complex systems of gathering materials, getting richer, managing your food and income levels but there is absolutely zero room to roleplay outside of the systems in place. You're left either grinding materials to up your numbers and expecting the fun to come later or completely alienated because everyone is flying around on jets just checking out the build and speaking in global chat. I want to spawn, explore for a short while to understand the situation I'm in and then bump into another player. The RP is in the players hands from there, that's the minimum I would expect from a RP server.
An interesting setting is key, though this is my most subjective point - I don't want to play family in a house or hit bricks repeatedly as a laborer, I can go out and do these things already IRL, games give me a chance of being in space or a wizard or in some age long past or a complete made-up fantasy. Yet still I see 2 family RPs and maybe one about shooting zombie bots.
Add-ons that fit are self explanatory. A couple to start with are a local chat system, my favourite is the RP names with local chat.
The last thing it should have is a reason to play, which if you've summed up the post so far, you'll realise is FUN. A lot of RPs miss this in their complexity of the systems. Great, I can be a millionaire after mining and cutting trees for 12 hours. Why would I want to? How about explorable areas that give me unique items. Think of Zelda as an example, you go place to place learning new stories, overcoming puzzles and challenges and are rewarded at the end of something particularly challenging. But the reward at the end isn't the reason you stuck through it, you did it all because it's interesting, immersive and fun. Now put some teamwork elements into your build and suddenly everyone's playing together as different characters, progressing naturally and having fun. RP systems right now are over emphasised and you can't see the wood for the trees. This pun works good cus I'm always chopping trees to make a living on RP servers.
I've typed a lot and I'd be suprised if you made it this far so I'll be quick on the things the server should definitely not have.
Jets is self explanatory, you lose all sense of scale and immersion on most builds because you can quickly zoom into the most interesting places and then leave.
Default global chat is again about immersion, you join and can hear people talking about cats or something and then you spawn on a space station. What happened? Who knows.
Irrelevant add-ons again breaks the immersion - having a bar fight in a medieval tavern and someone pulls out a rocket launcher. GTG.
An empty build is one of the most common things I see. Such wonderful worlds full of detail with absolutely nothing to do. I prefer these servers over servers with things to do which are completely grindy and dull because at least players can make their own stories and explore rather than watch numbers go up til their eyes bleed.
My final point. Excessive combat (that's just a TDM / DM - name it appropriately). Combat in BL is fun but in no way does it define your server as a RP server.
So I guess the idiot proof TL;DR: guide would be - make an interesting build. Get a couple add-ons to immerse players in the world - local chat, rp names and a couple unique add-ons for player reward works great. Fill the world with challenges for players to overcome.
Combat is fun but don't make it everything. Grinding is not fun so definitely don't make it everything. Find a balance, right now servers are either one or the other.