The good news is that your intuition is correct, and you got steps 1-3 correct. But, from the OP, you struggled with what action to take in step 4.
Honestly, it comes from what you're trying to prove. As a general rule:
If the conclusion you are trying to prove is a material conditional then start by either 1) make a sub-proof starting with the antecedent (Q) and see if you can derive the consequent (~P). That is what I did above.
2) Assume the negation of what you are trying to prove ~(Q->~P). This would have worked but it would require a longer and more complex proof.
3) Keep in mind more advanced proofs may require the use of Implication and De Morgan's laws.
Note: I used the website https://proofs.openlogicproject.org/ to
format and check my proof. Line 8's justification seems awkward to me, but
it's the notation used by the site. The logic is that R & ~R (5, 7 ^I)
violates the PNC and thus leads to an absurdity. Depending on the
book/professor you learned from, you may be familiar with a different
style or notation, but what is important is the concept of negation
introduction (~I) that I use at line 9, which is a key concept in natural logic.