If you are a student coping with your course.
I should say focus on what your professor's slice.

Basically speaking,
you'd better know the concept of investment.
you'd better find out the difference between investment and timing or gamble.

There is a famous investment model.
When you combine a lot of different securities together,
the possibility of suffering a capital loss will be reduced effectively.
You should know this.

Every professor will test you on this topic.

In summary,
investment is not rocket science.
It is not hard at all.

All you need is to understand its concept which is really simply.
Good luck my friend.