Say that we're writing sentences for Arizona and Velvet, but we don't exactly speak with a southern twang like Arizona, or Scandinavian like Velvet, but we have to write words the way they speak, because it's their character.

Arizona would be simple if you are familiar with writing Applejack. Velvet would be a bit more... challenging all things considered (Since I haven't really written any characters with that kind of accent)

You'd be shocked how far you can get by just following a few simple rules, when doing an accent.

I actually once played as a character in an RPG that had an accent based off of Velvet's. It was supposed to be a character that spoke English as a second language. I just listened to a clip of her voicelines a few times on YouTube, and wrote down a few simple rules. Let me find it....ah, here it is.

" "W" as "V". 'Thuh' as "Z". Use "U" instead of "O" sometimes."

That's literally all I used at first. Then over time I just memorised a bunch of random Norwegian expressions and curses and learned to insert them where appropriate, and added a few more phonetic quirks. And I just had her use slightly awkward/incorrect sentence structures sometimes, or express her unfamiliarity with exotic English words.

Added all together it worked pretty well. Or at least other people said it sounded good

6746692
So "What" will be "Vhat."

"The" will be "Ze"

At least, that's what it sounds like to me.

6746709
Yeah. So I vould talk like zis, ven I vas playing as her. I vould also say things like "hva?" or "nei?!" instead of "vat?" ven she vas surprised, for example. Zee pattern is simple but vorks rather vell, ja da?

One thing to keep in mind whenever you use a simple sound substitution rule when writing an accent, is that many words will contain the arrangement of letters, but not actually the sound. So you need to sound out each word, and see if it has whatever sound that your character has trouble pronouncing, then substitute in the sound that they use instead. If you just go by the letters of the words you'll make mistakes.

In my youth I engaged in way too much letter-substitution novelty dialect. As I've gotten older I've realized that this sort of thing is often more distracting than not and should probably be sparingly used. The phrasing and underlying character will usually do more for you than trying to remember to substitute v's for w's or whatever, and be easier to read in the end.