I'm actually comfortable writing all ratings. I know I don't write much NC-17/Explicit stuff under the name hells_half_acre, but I HAVE done it elsewhere and enjoyed it immensely. And no, I've never set out to write one rating and written another - if I want things to be porny, I write them porny, if I don't want them to be porny, then I don't put sex in.
The amendment to that is that Americans rate for sex and Europeans rate for violence. I tend not to rate for violence (ie: I use the American method of rating), so that's the only area where I might be writing a higher or lower rating than I'm claiming without realizing it - there might be Europeans reading my fic who are like MY GOD, YOU JUST CHOPPED SOMEONE'S HEAD OFF IN THIS G-RATED FIC! I'm APPALLED! But, I kinda doubt it, because no one's ever actually said that. Also, if there's swearing or graphic violence, I usually jack the rating up to "Teen" just to be on the safe side.
Most important is to warn for spoilers! Nah, probably most important is to warn for any rape, sexual assault, or dubious consent. Recently, I wrote a fic where someone had an anxiety disorder - and although I didn't think I was graphically/viscerally describing the anxiety attacks at all, I got a few comments about how with the way my writing evokes emotion and also the fast-clip of the action at that point, I HAD actually set a very anxious and heat-pounding pace to the chapter... and one of the commenters suggested that I might want to warn for Panic/Anxiety, and so I did immediately.
I don't think I've ever warned for anything strange.
16 – Summaries – Do you like them or hate them? How do you come up with them, if you use them?
God, I hate them. I really really hate them. I'm horrible at coming up with them and if my fic doesn't get many hits, I always blame the summary before I blame anything else. How do I come up with them? I try to think of a way to say what the story is about without giving away anything and also being funny and/or curiosity-inducing... basically, I try to come up with the equivalent of "click bait" only for fic and far less obnoxious or obvious.
17 – Titles – Are they the bane of your existence, or the easiest part of the fic? Also, if you do chaptered fic, do you give each chapter a title, or not?
Sometimes they can be the easiest thing. The Case of the Unfortunate Brother was one that was really simple to think up and I love it. Same with Lies Were Kept Simple, which is probably my favourite title I've ever come up with next to Damned Demented Demons (also super easy to come up with.) The nice thing about coming up with a good title for the first story in a 'verse is that it can provide the titling-scheme for the rest fo the 'verse too, which is why the demented'verse, for the most part, all have alliterative titles for the longer stories.
If they're not easy though, they're IMPOSSIBLE. I tend to either go with poems and sound super pretention such as with "I Imagine the Gods Saying, We Will Make it up to You" (which is just WAY too long for a title, even though it's possibly my favourite poem ever and I love it.) Or I go with too brief and vague and end up with The Time Traveler, which doesn't tell you really anything about the fic and no one is interested in it at all. (Yes, I'm still bitter that apparently that story sucks and no one likes it... I really should write a longer less opaque version of it some day so that I can get all those sweet sweet Stucky hits.... but, I've probably missed my window for that sort of story now that Civil War is coming out.)
Some titles, such as "Men of Legend" were actually originally a placeholder for a better title, and then I realized there was no better title.
I don't title each chapter.
Amendment to my previous answer to 7:
7 – Have you ever had a fic change your opinion of a character?
When I answered this before, I talked about my own fic, and also my inspiration for Draco in the demented'verse (which was from someone else's fic that changed my opinion of what Draco could be.)
HOWEVER, at the time I completely forgot about the journey I took in my teens with Due South fic and the character of Ray Kowalski. In Due South, Ray was a character who, as one of the comedic elements of the show, would often-times forget words and or say the wrong word - such as saying hypochondriac instead of hypocrite... or just saying a sentence like "He was a hyper- high- hippo-" and then another character would say "hypocrite?" and he'd be like "yeah, that!"
So, when I was watching the show, I thought nothing of it - it was a character quirk, it was funny. Then I read a fic once that brought up the fact that Ray was a former boxer, not to mention a fellow who tended to get injured a lot... and that aphrasia was a real thing from which people who were oft hit in the head might suffer.
Now, of course, aphrasia, when you do more reading, is a LOT more complicated that what Ray seemed to display, but that fic still got me to see a "quirk" in a whole new light... mainly, I had never considered before that intelligence and the ability to articulate your thoughts were two completely different things and that there were people who could be extremely intelligent, but have a disability that made them sound hilariously inept at times (like Ray), or simply they could have difficulty articulating their thoughts in general. For the extremely arrogant teenager that I was, that was a needed revelation, both in terms of looking at the character in a new light, but also cutting real people some slack too (including myself).
Now, of course, by the time I got to doing my Masters at unversity, I realized that the inverse was also true, and that people who could speak eloquently and sound super intelligent could also be gigantic idiots who just happened to be good orators.