Etiquette in play online is something that is rarely talked about but is an important thing to know in order to get along with everyone.
Play on a Mornington Crescent server is, strangely enough, remarkably similar to chatting online in many respects. Be respectful, don't use harsh language (because some people play from work where that sort of thing is scanned and blocked) and always remember that ambiguity breeds confusion. A bit more explanation might save someone from misunderstanding your joke as an insult, for example.
People usually play about once per day - a response within 24 hours for anything is a blessing, not an expectation. This also means that in many games you should not play more than once; if the muse strikes you might play up to three consecutive moves in a word game such as late arrivals, but more than that is considered spamming. In Mornington Crescent, following your own move is right out, of course, and even having only one other player between two of your moves is looked down upon.
Put bluntly, you are not cleverer than everyone else and you do not need to demonstrate this in any way. Crescenters value humility and cogency more than they value brashness and show. Your brilliance will shine through anyway. This also means that putting things bluntly is a last resort.
Games rarely need any more confusion than the existing players can already generate. Resist the temptation to mix things up a bit in any game you are not already established in. Dollis Hill loops and Ruttsborough tactics should be eschewed in most games except where specifically allowed or strategically significant. Once again it is worth mentioning the idea of polite play being more important than winning.
Starting a new game is a matter for careful thought and should never be done on a whim. Games are for showing the collective creative genius of the assembled players, and whims rarely encompass such goals. If you have a idea for a new game, and there seems to be a game slot available, your first step should be to check the chat game on your server - almost always the first game in the list - and check whether any ideas have been discussed. If not, put forward your idea and wait for comment. Only if you get someone else liking your idea should you consider posting it. Time is not of the essence on a Mornington Crescent server - good ideas and good play are.