Just spent a bit of time reading through this thread - wow, there is certainly no shortage of great ideas out there. However, what I do sense is an awful lot of worrying and hesitation. So here is my little slice of advice - stop worrying and start writing.
Is this a cliche? Is it overused?
Perhaps, but there is nothing new under the sun, just concentrate on writing a good story with interesting characters.
What if it is crap? What if my writing is rubbish?
That's what the delete key is for
and you will get better the more you do it - read lots, and lots and lots of quality books of good variety. This way you can learn what works, what's good and what's not ('hey, I love Glen Cook's characters, how does he do that?' and 'wow, Goodkind's plots are so complex' - ok, the second quote is for comic effect)
My world is not ready! It's not fully developed yet!
So, start writing and do it as you go. You will almost certainly find that the details will leap to mind as your characters move around and encounter your world. The world will continue to develop as yor characters explore it - enjoy it!
I don't have time!
What's the rush? Just write when you can, relax and enjoy it!
I realise some people (like me) dream of getting published but are not truly bothered about it, and some are desperate to get published. Personally, as I have said before, I don't write to get published, I write because I love to write and create. This world of mine, the people in it, their loves and hopes and fears and the dangers they face are all down to me. Will they live or die? I don't know yet - I may think they are essential and find them suddenly in an impossible situation from which the cannot escape - do they die? Well, yes, anything else would be contrived and deceitful.
I am well into my second book and have written large chunks of others as well as huge amounts of ideas, notes, maps, short stories (character backgrounds) and so on to help but it has taken me 12 or so years. No rush.
Do it because you must
What are you waiting for?