when you move up and drop to one table , don't switch off when you fold your hand ..really focus on the play put players on hands make notes on their play andand really fill the time between times you do play a hand. That way you won't be taking hands past the point where you should dump them simply through boredom.then as soon as you are comfortable with the play add an extra table, you'll start playing more hands in total but same number per table and I found that that helped my play, but the single tabling had put a baseline in to help understand the play at the new level.
As for the play , I did find that there was a difference between 2 and 5NL. It help if you can find out whether people are multi tablers as there are quite a lot of people doing 10+ tables at stars.There will be fewer callers but still loads of fish stacking off with bottom pair.