DON'T think that all eyelash extension technicians are all the same.
Don't be afraid to ask questions — after all, they’re working near your eyes. Be sure that they have an esthetician's license and are certified to apply lashes, and ask to see pictures of their previous work. Quality eyelash extensions should look defined, straight, and natural (even with lots of volume). If you can see glue, lashes stuck together, or crooked fibers, find a new technician.
DO compare prices.
For the most part, the adage "you get what you pay for" is true when it comes to eyelash extensions, and price dictates quality. But some lash artists overcharge and some undercharge, which is why looking at pictures of their work is so important.
DON'T go to a lash tech that hasn’t taken courses from a reputable company.
Again, do your research on your lash expert. Believe it or not, you can learn how to apply lash extensions on YouTube, but do you want self-taught technicians applying glue near your eyes? Not only do training courses explain how to properly isolate each lash for extension application, they teach technicians about the chemistry behind the work and the ingredients in the glue. You need to be sure that they can verify there is nothing harmful (like formaldehyde) in the products they are using on your lashes.
DO know that lashes can be customized.
Just like your real fringe, extensions come in different thicknesses, lengths, and levels of curl to perfectly blend into your real lashes. You don’t need to have superdense, dramatic lashes — you can get more natural extensions that look like you've just applied a few coats of mascara.

POPSUGAR