Mock interview

will help you figure out

a) strengths

b) what to improve and where to read things from

example in LLD usually you have to do this :

1. Class Diagrams (Use SOLID while creating these)
2. APIs, Access Pattern Deep Dives
3. SQL vs NoSQL (Why one ?)
4. Writing clean code.

See a sample here : https://github.com/jalotra/machine_coding_example