I Want Fuller, Thicker Lashes. What Do I Need to Tell My Artist to Do & Use?

First, your lash artist should be certain that your natural lashes can support your request if you have very short, sparse lashes that are very thin, Sylvia would recommend that you do not walk away with the thickest, longest lashes available.  Instead, your lash artist should recommend a design that will not cause harm to your natural lashes.  To add some fullness without weighing down your natural lashes, your lash artist can use the tape back method to add in some very short lashes (6 to 8mm depending on the longest lash length you selected) to the 2^nd and 3^rd rows.  You could also have your artist apply Volume 2D if your lashes are very thin or 3D to 6D extensions if your natural lashes can support them.  2D to 6D lashes will be more expensive than classic one-on-one eyelash extensions because of the time involved and because more product is used.  You could also have your lash artist use Ellipse or X-wrap (flat) eyelash extensions to create the illusion of voluminous lashes.