1-Actually, attend the office hours- Most professors really like to teach, and the effort to show up and show interest is greatly appreciated
2-A little bit every day, keep it consistent, getting a spot on campus where you sit down and do work is really nice (soon you will notice that the same people are around and create a community)
3-Try to relate what you are studying with what you want to do in the future, or at least something that you find interesting.
4-Be resourceful: there is always someone teaching on YouTube or extra questions online. I
5-f you don't get a concept READ THE TEXTBOOK. Most times it is very useful to build up a foundation.
6-Stop doubting that you know things, your previous knowledge is always valuable, so give the exercises a go. You know more then you think!