Gerunds, infinitives, and subordinating conjunctions

Work work work'n away. Actually having a lot of fun learning the stuff I was shaky on, using Khan Acadamy. Maybe too much fun. But hey, I'm learning grammar! Finally! Why did it take this long to actually learn it? I think it was just taught in a boring and unfriendly way in grade school, and I never learned it there, and from then on all the teachers just assumed I knew it.

Main observation: there are A LOT of unfriendly jargon words used to describe things. But what they are describing is not so unfriendly. There is a lot though, that I don't know. But really, I've gotten along fine without it, simply by doing the "does it sound funny" test. But every now and then, a writing teacher would say, "you can't make that a sentence, it's a gloop-ity-glargle-phraxis (I'm trying to give you my experience, though I now know what the actual word is.) And I would be confused because the sentence sounded just fine, and never really understand why it was wrong.

Now I know that many of those were dependent clauses that I'd made into sentence fragments and though we use them all the time in speech, they are technically not "proper" written English. But I also know that, because they are used in speech, they are fine for informal writing, or as dialog. You just have to know what you're doing. And that's why they always passed my "does it sound ok?" test but often got caught by my writing teachers.

Also, I'm learning all sorts of juicy tidbits, like how it's ok to start sentences with "but" (or more generally, with conjunctions. (I had to look that word up. Grammer-speak continues to elude me) and end them with "for" (or more generally, prepositions.) It's true! See for yourselves (yourselves: 2nd person plural reflexive pronoun):

https://www.khanacademy.org/humanities/grammar/parts-of-speech-the-preposition-and-the-conjunction/types-of-prepositions-and-phrases/v/terminal-prepositions-prepositions-the-parts-of-speech-grammar

https://www.khanacademy.org/humanities/grammar/parts-of-speech-the-preposition-and-the-conjunction/correlative-conjunctions-and-starting-sentences/v/beginning-sentences-with-conjunctions-the-conjunction-the-parts-of-speech-grammar