V’s go left to right, check marks have the long tail on the left (but I recall doing it the other way around when I was younger, then noticing other people didn’t do it that way and subsequently conforming to THE MAN’S check mark protocol), and I’m a straight up-and-downer, which often gets the outside of my hand covered in ink when I’m finished. I had a teacher who told me to turn the paper when learning cursive–it didn’t work the slightest bit, because all my letters then leaned back. I got D’s in penmanship my entire grade school career, but my handwriting really isn’t that bad.
Freak here,
Right to left. My handwriting is quite horrible, so I find if I go left to right, it’s looks all kind of squishy. If I right right to left, it comes out looking much more elegant. Kinda like a drawing of a bird in the distance, nice swoopy wings.
Wife also a lefty though and she’s a left-to-righter. I never figured out how we got over that hurdle.
Wally
Left to right. I also tilt the paper almost perpendicularly. I’m just weird that way. But my check marks are back to front – the tail is on the left.
My v’s go left to right. I’d guess that the reason so many of us of write that way is because your hand is going that direction while writing a word anyway. You’d have to sort of double-back if you wrote one letter right to left.
My checkmarks go right to left and I write them in front of whatever I am checking. Some people are astounded by the fact that my marks are on the left side of the page, and I haven’t figured out why. 
I mean, if you can tell what I am indicating, who cares which side of the word it is on?
I write with a curved wrist. My mom, who is also left-handed, does not.