Not sure what documentation is required at your school so this might not fully apply, but:
1. Stay organized. Make yourself a binder for all of your clinic crap. Photocopy everything that is important--- I.e. daily operative sheets that make you eligible for competency, step cards, etc. competency forms, point tallies for graduation requirements).
2. Save all of your lap paperwork-- add it to the above binder. Among other reasons, it will benefit you to have a quick go-to when you have to write the same lab script again
3. Be up front with your patients. Make sure that they understand that your graduation is dependent on them showing up for several long appointments. Tell them that the dental school setting is a place where they sacrifice time instead of money, and there is little tolerance for no showing (even if there is, tell them there isn't). In the beginning I was too nice about this and I suffered the consequences. Now that I am up front with my new patients they are much less likely to no show.
4. Don't stress about what you don't know. The time between 3 and 4th year is one of the most drastic in terms of your dental knowledge. Absorb as much as you can. Mistakes are going to happen and learn from them.
5. Don't assume crap is going to get done by schedulers, assistants, professors, whatever. Constantly follow up on things to the point of being excessive until you realize you you can cut slack on and who you can't.
6. Push yourself to go above and beyond in your 3rd year. If it means doing extra lab work when others are not, or (depending on your school) utilizing extra time in the clinic when you aren't required to-- do it. Though I am just starting my 4th year, this is something that has really set me up nicely for the next 12 months.
7. Karma is real. Don't hoard difficult graduation requirements or competency lesions if someone above you needs them to graduate-- or you might end up in their shoes come graduation. Of course there are exceptions to this, but in general try to pay if forward to upperclassmen trying to get out ASAP.
8. Professors appreciate detailed yet concise chart notes.
I think that's about it. Good luck- your life in dental school is about to get infinitely better!