Dou

What is the meaning of dou? As in "dou suru" and "dou yatte". Is there an English equivalent? Cause it seems to me that it can mean, what or how. Please help me clarify this, thank you!

It means "how?" "what?" or "in what way?" so there is no single equivalent in English. You need to learn it together with the way the word is used in sentences/expressions.

- Dou omou? (What do you think?) (Incidentally this is part of the reason why many Japanese students tend to say "How do you think about it?" when trying to ask opinions of others, where they should say "What do you think about it?)

- Kore kara dou suru?" (What do we/you do from now?)

- Dou yatte kaeru? (How do you return home? In what way/By doing what do you return home?)

- (Pointing at a Rorschach inkblot test) Dou mieru? (How does it look (to you)?)
Of course you could say "Nani ni mieru?" (What does it look like?)

- Dou benkyo shitara, seiseki ga agaru? (How should I study to get my grades up?)