There is a little bit in the column of my text book:
significant figures
This is to remind you to give your answers to all calculations to a degree of accuracy which is consistent with your apparatus and data given. If you have to determine how much solution to run out from a burette the answer can only be to the accuracy of the burette. Your calculator may read 22.7134 mL, after doing the calculations, but your answer has to be to 22.7 (3 sig figs).
Just some random stuff i can remember about them:
-Increase in amount of numbers, eg 4 sig figs /3 sig figs increases the level of accuracy, so 10.9 (3 s.f.) is more accurate than 11 (2 s.f.)
-From personal experiece; DONT ROUND TOO EARLY, i have lost marks from doing that, and you can only give ure answer witht the same amount of sig figs that the data given/collected has.
-In numbers less than zero the zeroes after the decimal point are not significant, if in doubt convert to scientific form (0.00217 = 2.17 X 10^-3)
I hope that has helped, Good luck for your test!