Before you even begin to draw a caricature, it is always best to study who it is you want to draw. If you don't know what the person looks like, it will make it even more complicated to try and draw them.
This is where you should try to find the key features that make the character who they are. As a demonstration, I have listed a few key features that makes Daddy Yankee recognizable to his fans.
Firstly, his ears have a very odd shape to them.Take a look st how they are almost elf-like.
Secondly, we'll look at his smile. In every photo he seems to have a very sly smile.
The third feature compliments the second because his smile creates dimples.
Take a look at the proportions of the face and imagine the dimples to help you recognize the placement.
Lastly is his sunglasses. In every photo he is wearing an aviator style pair of sunglasses
Now with these key features we can figure out what we can exaggerate.
Next would be recognizing the proportions of his face. His face is very long and his chin seems to expand out towards the bottom. Always study a reference of the person you want to do a caricature of.