1. Advertisements
2. Paid promotions
3. Affiliate Marketing

These are the three main sources to make you money via YouTube.

Advertisements are the standard way and won’t make you much.

Paid promotions are when you do a marketing through your videos for upcoming or recently launched products like mobile phones, camera etc. and the money you make will be dependent upon the offline negotiations you have with the company whose product you are promoting.

Affiliate marketing is when a user likes a product you use and describe in your videos, buys that product via a link provided by you and then you earn commissions on the sale of such products.