I only put them on for ballroom competition, not for real life, but second the suggestions for videos and practice!
The brand of lashes makes a difference too...some have ridiculously thick bands that look obvious and don't mold well to your eye shape. I recommend Ardell because the band is thin and flexible, and also because they are budget friendly so it's no big loss to blow a few pairs practicing.
I also recommend the Revlon lash adhesive if you can find it. You might have to search online. Duo gets all the attention, but it is not latex free and it does contain formalin, which is a form of formaldehyde, so both of those things make it less than ideal for sensitive eyes. Another plus for the Revlon...a brush applicator so you can control the amount of glue more easily. Duo is just a tube, and it always squirts out too much and then it's hard to spread it out evenly. Can you tell I hate Duo?
Also, the videos will tell you how to trim the lashes. Did you do that? If they are too big for your eyes, that might explain the trouble with the corners not sticking down.