First, curl your lashes twice. Curling the lashes really helps to lift the lashes and open the eye - a crucial aspect of the Bambi look.
Next, apply your mascara first to the middle section of your upper lashes - then apply to the inner and outer sections of your lashes. As you apply, don't press really hard on to the lashes. Lightly work over them lifting up with the wand as you go. Remember, you can always apply more mascara, but you're looking for a flirty, upwards looking lash - not a thickly coated, heavy lash. An important note here: Clean that wand well before you apply! You don't want that thick clump of mascara that hangs from the end of your wand hitting your lashes and getting clumpy. Wipe that end off pre-application!
After you've applied your coating of mascara to your upper lashes, apply a second coat of mascara to the outer 1/4 of your upper lashes. Do so while holding the mascara wand vertically. Apply the mascara in a "straight-up" way to this outside section of the lashes. If your last few lashes are pretty long, you can even pull the wand straight out horizontally at the most outer edge to get the last 1-2 lashes to be in true Bambi fashion. Be careful if you try this part - to only touch the last 1-2 lashes. You're going for a very open, vertical lash line in the last 1/4 of your lashes, and a horizontal taper out for the last 1 or 2 lashes (depending on your natural lashes).
Apply a light coating to your bottom lashes, and voila your Bambi lashes are complete!
