1. Each lash needs an individual approach. We never focus on the direction of natural lashes, they can grow in completely different directions. So you always need to find where to place a lash or a fan to set the desired direction and have a sufficient contact area.
2. Set the direction gradually, slowly increasing the angle of inclination. Focus on the neighboring eyelash, as all the lashes have to be parallel to each other without crossing or diverging.
3. Pay attention to the direction of the lash TIPS! Lashes/fans may be parallel to each other at the base, but overlap at their tips. As a result, the direction won't look the way you want.
4. Use the framework method. For many lash techs, this method is much more convenient to set the starting points for the whole work direction.
5. Work on the fan geometry. Fans should be as similar as possible and not very wide, then you'll achieve an even direction.
6. Let a lash dry. There's no need to immediately extend a neighboring lash. Firstly, there's a real chance to get a stickie; secondly, you can by your own change the direction with tweezers, since the glue hasn't dried out to hold a fan yet.
7. Check if the distance is the same everywhere. If the distance varies, then the direction will vary as well.
8. Practice. Not only with clients but alone too. You can take a sponge, put on the edge some false lashes in a row (one by one) and then extend every one of them with a lash or a fan, setting a classic fan direction. As a basis, you can use a lash strip.