Are a majority of your results off-topic? If so, look at some of these false hits to see why you are retrieving them. Similarly, do you see any records that are on-target? If so, take a look at some to see if you can identify additional terms to add to your search.
Use this exercise to consider modifications to your search terms and/or your search concepts. Continue to revise and refine your search strategy until you are satisfied.
Paste the PMID list you generated in Step 1 into PubMed and run a search. This result set of included studies represents a "gold standard" set of articles that should be found by your search.
Combine this result set with your completed search using AND. If you don't find all of the included studies this way, some critical terms are missing from your search, and you will need to modify it. Use the studies you aren't finding as clues to which search terms might be missing from your search strategy.