It's by no means the best guide out there nor will everything I say be universally agreed upon, but that's just my experience and the advice of people far greater than me.
- Write your whole story first. An imaginary audience can't demotivate you.
- Look over the first five chapters, and try to see if there's any of these chapters that would make for a more exciting start point. Be ready to completely trashcan your original start point. You're looking for a point in your story where there's only 2 or less characters, the MC is immediately introduced, next to no worldbuilding, and there's an easy hook sentence.
- On the hook sentence:
DO NOT: "In 300 Adentum time, there was a great magical historical empire that set down a treaty of cooperation with their neighboring states, and everyone loved them, and the princess that everyone adored, because she was very beautiful... <Did you glaze over yet? Yeah, that's why this isn't how you wanna start.> and so the whole set of this hidden history rested upon the pink sandals of princess who-cares. Of which, our main hero had unknowingly decided to steal as he was wrapping up the real job, having successfully heisted his target. This last second on-the-whim decision had the whole compound suddenly chasing after him."
DO: "Oh shit, I'm going to die because of these stupid pink sandals."
- Post your fic to another site first, and gather initial feedback + a small core following.
- Post on RR two chapters a day for max efficiency, and mobilize your readership once you have enough chapter to retain new readers.
- Everyone's a critic. If you make your character OP, they'll yell at you for making a 2D character. If you make your character flawed realistically, they'll say the character's annoying or doesn't fit their self-insert imagination. If you make your character fake-flawed in the 'my biggest weakness is how humble I am", guess what - they'll say your character isn't 'realistic'.
Placate, and ignore. Do not argue back or defend your character. If they're posting, they can't be convinced to think they might be wrong. Just trust the process and the path that you picked and keep going. It's your story, so write it.
Actively seek out and destroy redundancy. The writer's brain knows what it's trying to get across and easily puts the same word into paragraphs multiple times. Readers brains notice this and get annoyed.
Eliminate any unnecessary words. The word "that" can be removed from almost every sentence without changing the meaning one bit. Getting rid of it makes these sentences less clunky.
"Toward" or "Towards" - Both forms are technically correct; however most people, including many talented indie authors I've read, aren't aware that "Toward" is the preferred form of the word in the United States and Canada while "Towards" is the preferred form in the UK. If you're otherwise using American English, go with "Toward."
Use the word "get" sparingly or not at all. It might be fine in dialogue, but in almost every other case, it can be replaced with a more interesting word.
Know (or at least look up on Google) the differences between lay, lie, and laid. They aren't interchangeable, and people use them incorrectly a lot of the time. Same with "Their," "There," and "They're," and "To," "Two," and "Too."
Show, don't tell, unless you're summarizing mundane things. If your character went to the bank yesterday, you can tell that because it's only of minor importance. If your character discovering the secrets of life, be descriptive about what they're experiencing.
First person, third person limited, or third person omniscient? I'm personally not a huge fan of first person, and many shared worlds like Star Trek, or The Forgotten Realms (back in the good old days when WotC still published fiction) required writers to write in third person limited perspective. That's my preferred mode. If you want to jump from one point of view character to another, put a break in the text. Some writers like third person omniscient, and it does make describing combat scenes a little easier, but many readers find it confusing.
When you're describing something, it helps to do so from the point of view of the character who's head you're currently in. "The manor was blue" is so much more interesting when you say something more like, "Rathorn regarded the blue manor." You can then go on to give the character's opinion about the thing you're describing, if he or she has one.
Write sentences shorter to increase the tempo. In a combat scene, short sentences are good. When writing description, longer, more complex sentences are usually more appropriate.
I'll edit this if I think of with more.