I've been looking through the specimen papers (such as for AQA Trilogy - aka double and Edexcel biology) and I have noticed that the required practicals take up a large amount of each paper. In fact, in the biology papers I have looked at, between 33% and 40% of the marks are related to the procedure in a required practical or the science related to a required practical.
There are tons of resources with details of required practicals. First of all, the exam boards themselves have produced detailed documents with procedures and possibly even sample results. You can find AQA's practicals here and Edexcel's practicals on this page (scroll down and click more).
There are also videos of people doing these practicals. These videos are very useful as you can see someone doing them and they can remind you of what you did. Some of these videos say that they are for particular specifications, but many of these practicals are the same over many specifications. Also, remember that if you are doing double science that you do NOT need to do all of the practicals.
Make sure you know what course you are doing and which required practicals they have.
Here are some video channels:
Free Science Lessons
Maths skills in biology
Also, 10% of biology papers have to relate to maths skills. This is great news as there are very few maths related parts of the biology specification and so this means that these maths related parts are almost guaranteed to turn up.
Here is a great post from https://www.my-gcsescience.com/ on maths skills in biology.
Be sure to check out all of the blog posts from that site as they are very useful.