Original content still has the largest potential to earn a reward on Steemit. You can split it up your time however you like though, spend 20% of every day's Steemit time or dedicate a day to writing a post.
You might find that people view & upvote your post after reading your comments.
Fair enough, I suppose I haven't seen the return on original content yet - especially compared to my comments - but I'm sure that's because I've only been here less than a week.
Here's how I see it: I can always get "lucky" and have a well written post get lots of comments, upvotes etc...BUT the odds of me getting lucky this way increase with the greater number of followers and Steem Power I have. It's like playing blackjack - you can win and bust the dealer at any time, even when they are showing a 10, but you have far greater odds when they are showing a 5 or 6. For now I still miiight write a post or two to test the waters, but I'll probably budget only 5-10% of my time for that right now...though I definitely plan to expand that as time goes on and my account grows.