How many times do you review a lesson until moving on? Do you just complete it and go to the next one or do you spend time reviewing everything you've learned until you reach a specific goal before moving on?
Depends on my comfort level. I usually just complete a lesson once, and move on, but if after completing the lesson, I don't feel 'good' about it, I may redo it. Generally, I just rely on the Strengthen Skills option (which I earn at least 30 points worth of a day) to keep the information fresh in my brain.
Some people like to complete a lesson until they get it perfect (and there is nothing wrong with that-it may work for them), but I warn against that because DL only has so many sentences, and if you complete the same lesson until you get it perfect, you get into memorizing the sentences territory instead of keeping your brain translating.
Everyone has a method that works best for them, and I am sure that you will find your own. My personal "formula" for each day is, one review and one lesson in the morning, and one further review in the evening. There have been a few spots where the going was hard, and I considered a three to one review to lesson ratio, but I managed to get past them.
For Spanish, I never reviewed, but in Portuguese, I learn a lesson, review it, then move to the next one. Or, I finish a skill, than review it from Spanish, then from the English tree.