When possible, praise the EFFORT, not the outcome!
In our house, when our kids fall down, we say something along the lines of "You're okay! Get up and try again, you can do it. [LastName]s try hard, we always try hard! say 'I try hard Mommy!' " Usually they will repeat the affirmation and try again. Of course, if they are really hurt, I will comfort as needed, but we ALWAYS have them try again. Or if they go under in the bath or something, we will have them stay in the tub until they are calm and help settle them, rather than let them end on a "bad note."
I have heard DD say "I try hard." to herself before, unprompted. Falling down is just one of the instances where we praise/encourage effort, not outcomes, but we also fall into the "good job" parenting trap often too. We're only human and a vague "Good Job!" just comes out so naturally.