Even in biology,  you have various classifications of flora and fauna. You have a generic case and also exceptions under each case. Even diagrams like eye or ear, you divide them into internal and external parts – then functions of each part to get a overall picture.

Almost same strategy only. Generally in physics,

1. We take the basic law,
2. Put a mathematical form of the same
3. Use a diagram
4. Apply some mathematical principles
5. Get some more details and modify the mathematical information further and arrive at another conclusion based on the new one
6. Mostly with LHS and RHS side, we understand whether the quantity on both sides varies directly or inversely with respect to one another
7. Once you understand this, along with the videos, you should find it easy to follow any derivation
8. Try doing the derivation 4-5 times immediately as soon as you learn, so that you understand that better
9. Also, periodic revision is essential so that you do not forget the same

So have a positive mind that you will be able to do derivation as easily as concepts in biology