Don't be afraid to ask if they use high quality anesthetics. Depending on the Artist, the medication will vary. However, the numbing process should take place in two steps to ensure client comfort:
Good anesthetics is expensive, so some Artist use poor quality to save money.
Prior to your Eyebrow or Lips procedure, exfoliate the area several times during the week using gentle micro-beads, facecloth, or buffing pads. By removing some of the dead or dry skin, you'll have a better chance of the anesthetics to penetrate the surface of the skin and be more effective.
If you're extremely sensitive, try taking ibuprofen before and after the procedure.
San Ramon, CA