A pleasant colour/format scheme.
A simple usage of bold, text colours, HR lines, and proper spacing can go a long way when it comes to intro posts. Proper understand of which colours look nicely with which (whilst have readable text) is similarly appealing when it comes to banners. But generally, I want to see that GM's aren't just limited to using plain text in every paragraph without a little bold, font change, or colour. Similarly, I want to see that GM's don't get too excited and sprinkle glitter and pink and GIFs everywhere like a unicorn fart.
A pleasant GM.
It's not just the banner or the introduction that's going to draw me to your RP. It'll be you, as the GM. Everyone has their own idea of a 'pleasant GM', but here are the basics I'd like to see. I want to see that you can treat players fairly, know how to interact with them, and I want to see that you know how to run an RP in general. Even if you can't properly run an RP and you're new to the whole GM'ing thing, I at least want to see you trying to be communicative and friendly with your players! For example, if you accepted my sheet, why did you accept it? If you denied my sheet, why did you deny it? I like to discuss, ask questions, etc. with the GM often, and if I don't feel like I'd get along with them, I move on.
Knowing how much to write for an Interest Check.
Interest Checks are what initially reels people in to the idea you have in mind. If you just say something like 'hey guys I've got a sick fantasy plot planned who's in??' this shows me that as a GM you haven't pre-planned much, and I like my GM's to lead the story rather than letting other people create the majority of it (though I am aware those sorts of RP's where players create are a genre of it's own and a respect that. Just not my cup of tea.) However, writing too much in multiple huge, headache-to-read paragraphs dissuades me somewhat if there isn't a brief introduction summarising the whole thing at the top.
Innovation.
Innovation is probably the thing I crave most in an RP, though it's a term some people would scoff at me for using. Regardless, I don't want to see the same cut and paste premises I've seen many times before. Whilst I'm not asking for an idea that's never ever been done in the history of man, if you're using a similar formula other RP's/typical stories use (such as saving a damsel in distress, having a group of trained badasses to dispense justice everywhere) I want you to put your own twist onto it. I don't want you to completely copy common themes (though basing ideas on other things is fine) and I want to see you put heart, soul, and your own ideas into the RP. When you're GM'ing an RP, you're projecting your creativity and ideas you've had built up for a long time to other people. So even if not everyone's going to like it, make it special and unique in your own way, and it's definitely going to interest people with the same mindset as me.
Basic Grammatical Ability.
If your idea is great and sounds fun, and you've put work into it, I don't mind a few typos. They're honest mistakes, and pointing out slight mistakes is pretty dickish when a lot of soul went into writing something. But... if your writing is incoherent, with bad use of commas and full stops to pace your introduction, and with generally undecphierable spelling mistakes everywhere... yeah. This one is sort of obvious, but I still may as well bring it up.
Passion.
This one's simple. I want to see that you're interested in running this RP, and you're looking forward to doing it. When you present everything in a half-assed way, and talk about everything in a half-assed way, and you've clearly made like 1000 underdeveloped RP's in the past, I can tell you're just spamming out random RP's until you find one that a few random people will say 'yes' to. Even if it fails, one big and well-thought out RP is better than loads of small RP's that you just posted because they were a little thought in the back of your head. Show me you care. Sell me this idea of yours.
Trying to create something that seems simple at first glance, but is a lot more when further looked into.
This one isn't essential at all, but it's still something I like. I like prying. If you're able to create an intro post, title, etc. that's simple to read and understand on first glance, but on second glance, you can look into and discover a lot more about it, that's always something I'm impressed with. Things such as symbolism, words in other languages that just seem decorative at first but reveal a lot when looked into... etc. The main eye-catcher for me to join plots is if they're interesting and unique compared to my previous RP's, but if they hold a deeper meaning, that shows me you've got a good idea of what your plot is and that it's going to be well developed. I'm going to look forward to seeing what you have in store.
I could write more, but a lot has already been pointed out by our friendly neighbourhood ferret. These are just some of the things I personally like to see when you're introducing an RP to me, but with all the different people out there, 'the perfect RP' will be differently perceived by everyone.
