Tips for scraping that first?

I just finished year 2 of my 4-year Chemistry MSci course (well, pending a resit in a few days). I did the calculations and it turns out that, in order to get a first, I need to average around a 75 for the next two years (my average is 63 so far).

The main thing that I feel has prevented me from averaging a first is that if I don't understand something in a module, instead of taking action straight away, I wait for the next few lectures hoping that it will all tie itself together and I'll understand in the end. Obviously this doesn't usually work out and I end up cramming for the exams, and only understanding the content on a superficial level, which doesn't give me a good base of knowledge for the next module. So if I get over this fear of looking stupid and actually engage with the lecturers, I think I can increase my exam grades. I don't have issues with coursework and tend to score around 75-80. Also, I go to a top 10 global uni.

For anyone who's been in a similar situation:

1. Is this even realistically possible?

2. If so, what would be your tips for increasing grades in the final years?

Thanks in advance.