@jonno-katz if you aren't making anything from curation (and this is the case if your SP is small, say <1000), then you might as well do exactly what you are doing. Vote for purposes of approval to increases rewards authors you think should be rewarded more and exert a small influence on the type of content you want to see. It seems to me you are doing it exactly right.
@anonymint your comment is oversimplified. Remember, early votes are worth lot more than late votes. Most blog posts you encounter are already heavily voted, and late votes on even posts with high rewards are still virtually (if not literally) worthless. Most comment posts have 0-1 votes. Opportunity is not always at the location with the brightest spotlight on it.