My advice is to just submit and submit. If you have stories, boost them out! I've had stories rejected by token-payment mags and then picked up by pro mags so it's hard to judge sometimes who will like what. However you end up getting a good idea of what people want and what to write to get the mags you want after a bit and obviously you can go read the mags and be like OOOH they like stories with this theme, teeheehee.

I usually submit stories like this:

"Hi

Here is a story I'm submitting to your mag, thx for reading,

RJ."

If it's a pro or semi pro I also include my long list of publications.

It's also a lot easier to get into mags than you might think, although I suppose it depends what level you're submitting at.