There's not really a "best." You'll just have to go through trial and error to find the one that's most comfortable in you body. You might want to start with the ones that come with an applicator, just to make it easier to get it into place.
You'll also want to get panty liners to wear when you're wearing tampons. You might even want to wear a light pad when you first start using them until you get the hang of it. They leak --- and hurt --- if they're not in the proper position for your body, and they don't act as plugs when they're full. You'll want to have a back up in case you leak.
And you might want to keep some moist wipes in your purse so you don't come out of the stall with red fingers. Also, keep some hand sanitizer to clean your hands before removal/insertion while you're at school. Changing a tampon is not something you want to do with germy hands.
