I definitely agree don't be afraid to ask questions, or ask for help if you need it! Especially if you're doing anything involving giving or drawing up medications, double check with somebody if you're at ALL unsure about what you're doing. If you make a mistake (which I guarantee you will, more than once), don't beat yourself up about it or get defensive, but take that as a learning opportunity and try not to make the same mistake twice.
If it's not busy, take the time to ask questions about why things are done a certain way, why a patient is on X drug, how you can improve your restraint techniques, etc. If you're struggling with a certain task, ask somebody to help you practice if there's some downtime. Definitely ask them to let you try rather than just showing you how something's done.
Bringing a small notebook to take notes is a good idea, there's a lot to keep track of when you first start! The sooner you can get to the point of knowing what needs to be done next rather than constantly having to ask someone "what can I do now?", the better. Prioritizing is definitely an important skill to have, cleaning/organizing things is better than standing around chatting, but it can wait if there are patients that need taken care of.
Good luck, everybody has to start somewhere, and that's awesome that you've already got good relationships with the staff at this clinic!