Hi Sa09abr,
Sorry to hear you're feeling a bit nervous, but I can relate to this. I've finished my masters last September and graduated in December. I think looking back, the most helpful advice anyone could have given to me would have been the following:
1) Try not to feel too overwhelmed by things at the very beginning - the first couple of months are tricky because it feels like you're thrown in at the deep end, especially in a lab environment if you haven't had much lab experience before.
2) Don't be afraid to ask questions - the people in your department should be there to help you, and if you ask lots of questions at the start then you'll get to a point where you understand what you're doing very quickly (unlike me who was worried about looking stupid and then months later still looked stupid!)
3) Keep a really detailed record of your experiments and what you're reading.
4) Make a note of any deadlines because they can creep up on you suddenly without you realising!
And I think lastly just try to enjoy it all. If there are other masters students in your lab or that you have lectures with, try to socialise a bit too, because the work can be intense at times. I found the first couple of months very overwhelming, but once you get a feel for your project you do start to really enjoy the work, and it's great experience for if you're planning to stay in research and do a PhD. If you still feel anxious and want more info feel free to PM me.
Hope this helps, good luck! :)