Go for the eyes

Questions: 1) What does “go for” means on picture 3 & 4 mean?
2) What does “thumbs work the best”?

Thank you!!!

I means that you should attack (stick your fingers) the eyes because the eyes are a vulnerable part.

As for number 2 it means that thumbs are better for poking a shark’s eyes than your other fingers (index fingers, middle finger, ring finger, etc.). I don’t know the veracity (how true) of this statement as I have never fought a shark (hehehe).

I don’t know if you know this already but go for something also has the meaning, making a effort to achieve something. For example;

Person A: I speak Spanish, French and German pretty well but I don’t know if I should study Polish.
Person B: You always say that you are good at grammar and you have achieved a good level of knowledge in other languages, I’d say, go for it.