Pubic High School is okay, but there are bully's and people who spread many rumours about people they find are different from them to answer you're question about what it is like.
To answer you're question about the way you dress, it is very likely long skirts would seem "weird" or "dorky" to them but never change the way you dress just because they bully you about it, just keep it going smooth.
And last but not least, to answer you're question for the top things to know for high school, - You have to know a lot of stuff because they'll have some pretty hard stuff in high school and it is hard to figure out if you don't know much about them - Always be yourself because lots of kids will try to bully you to change the way you act or dress, don't let that happen. - Don't be tardy meaning be late for classes, because they have serious consequences for that in high school.
Those are the three top things to know for high school, now here's some tips:
1. Since you were home schooled you are not used to public schools so just keep it cool and don't be a nervous wreck because it will make you mess up a lot so just try to adjust the best you can and make some nice new friends.
2. Before you start High School, study on something that you would like to focus one when you get there, like say you like a particular thing in history so then before school, start studying on that thing before school starts so you will know more about it when you get to school and you do really well in it and then it is best to study a little on each subject you're taking in high school then you will know an equal amount in everything.
Hope this helped:) Lovepink123