I will start off saying ALL aftercare that your lash artist recommends IS important. But there are a few things that will really make the difference for YOU and how wonderful your lashes continue to be between fills.
SLEEP: Lay in a way that will not allow your lashes to touch anything! In deep sleep, your eyelids flutter and the constant friction between your lashline and the bed can definitely weaken the bonds. this makes a world of a difference.
BRUSH: Your artist should always give you a fresh, clean mascara wand after each appointment and you NEED to use it daily. Three times a day, actually, if not more! You wouldn't leave the house without making sure your hair is somewhat presentable, you wouldn't get out of the shower without some after attention to your wet hair, you wouldn't get out of the pool without straightening up the craziness, etc etc etc etc. Anytime you would think to brush your hair, brush your lashes. Brush them. Just do it :)
OIL FREE PRODUCTS: The fastest way to lose your new lashscape is to put oils around your eyes- especially before bed when your lashline is closer to the undereye. If you must, put those oils on your undereye in the morning, before your makeup routine. Oily products will break down the adhesive bond and leave you less flirty faster.
As mentioned earlier, follow all lash aftercare for beautiful retention and style! It does become habit, I promise :)