Daily Practice Strategy
Up until this point, My strategy has been playing a timed practice of each module each day (untimed for ones I can't "beat" the buzzer yet) and taking a single lesson a day, just one, to not overwhelm and to focus on repetition and retainment. As I've gone down the language chain I've pared away some of the modules that I definitely, absolutely know, but have added a "practice weakest words" practice in the "Vocabulary" section.
This has made sense to me as a good training strategy. Today for the first time, however, it occured to me that there are much more advanced users than myself who may have some additional insight on what works and doesn't work as a strategy for retention and fluency. Anyone want to share their successful training strategies with me?
My belief is that what you believe is good for you is... good for you. It does not matter if other learners seem to be quicker than you to "climb down" their tree.
However, for optimal retention and fluency, there are lots of theories other commenters will be pleased to list for you, including using other resources.
Maybe you could try to read some French (go to the Translation section, pick short texts, already translated, you don't have to translate, then check your correct understanding by clicking on the English translation).
And ask questions on the forum, you will get answers that may complement your knowledge with grammar or syntax points that Duolingo does not provide.
Bon courage !
I usually practice one or two of the previous units, then my current (half-done) unit, then I do a new lesson or two. I found that for me it is a good practice to repeat the lesson a few times because there are more sentences with new words than just 20, and by redoing the lesson I pick out almost all of them.
This is just my practice. I wholeheartedly agree with Sitesurf: if you find your practice good for you, it is really good for you.