Electronics

1. Familiarise yourself with the specification

2. Do practice questions online

3. Persist during practical sessions, especially when in theory things should be working but they aren't - it's just a matter of keeping an open mindset and thinking flexibly about the problem

"Eduqas" - website for online practice questions splits into chapters of the specification, has the whole specification

"WJEC website" - has a few past papers for big, end of year exams