Oh, I was excited before I started Sixth Form, and then I realized how difficult it was. It's difficult for everyone (well those of us who are human anyway). Don't worry about it being difficult. Focus on getting it done instead. It's a big jump, it's a big surprise. You have to experience it and then accept your fate.
I am starting Year 13 next week and I am so not excited now.
I posted this list on a similar thread before:
1. Make notes from textbook before lesson.
2. Make notes during the lesson.
3. Make notes after the lesson.
4. Do the homework, even if the teacher doesn't check it - it's for your own good.
5. Ask questions if you don't understand, even if it seems to be the stupidest question in the world.
6. Use separate folders/notebooks for each subject.
7. Participate in the lesson.
8. Prepare yourself, if you think Sixth form is difficult, you're in for a surprise, it's really difficult. If you think it's easy, then you are in for a big surprise. Just because it's less subjects, it doesn't mean anything.
9. I would say don't procrastinate, but since I am doing that now, I am not the one to talk. Try to limit the laziness though.
10. You have to study for end of topic tests - accept it. If not your teachers should make you re-sit it until you beg for mercy.
11. Do your work even if you hate the teacher - it's your life.
12. Try to do some work in your free lessons, just try.
13. If you get a part time job, make sure it's not more than 12-15 hours / week.
14. Start revising for your summer exams at the beginning of April.
15. Have a rough plan for your revision - what topics you are doing on what day. Don't try to shove it all in a few weeks, space it out.
16. What's that? Sorry? Your best friend brought these killer shoes? WRONG. Your best friend can't buy shoes, because it's a past paper. Past papers are best for practice and everything else. Personally, I like to rip them up if I fail - helps to relieve the anger and stress acquired from the other tips on this list.
17. Do things outside of lessons - it will help with your CV (that's not a new tip).
18. Forget the meaning of social life when you are revising for your summer exams, or at least try to limit it if you're a party animal.
19. Take pictures of your precious notes, so you don't loose them. Try using an app like CamScanner - it saves your notes to a cloud and you can group them by subject.
I probably have more, but I can't remember them. If you want to get subject specific, just PM me.
Also, no guarantees with that guide, but it does help. I was trying to be more original than just "Work hard."