Good for you Laural on hiring some one to do the job. There is always something to learn so don't feel like you missed out :-)
for me the BIG one is making sure that I have Yoast fully optimized. I spent HOURS one night going page by page thru the tutorial and think that it's right but I am still not pleased with my google page rankings. I also recently discovered that I had NO meta tags set.. I'm hoping that since that discovery was corrected a couple of weeks ago, it will help.