I have a personal ban on malls in which Kiosk salespeople aggressively chase down unassuming shoppers. However, I am a career salesperson myself and I have personally had some very aggressive sales gigs so I feel for you.
You have to consider your market, your product and your unique sales setting. Based on how most feel about being accosted by Kiosk salespeople while just trying to get from Nordstrom to Bloomies in peace, the best approach in this type of sales setting is to simply look friendly and be approachable, let the potential customer come to you.
Keep in mind, this is a sensitive product to force on people for a variety of reasons. A younger adult may come back at a later time when not shopping with mom, and mom may come back at a later time after having a health scare.
Also, E- cigs have had a lot of media exposure now... but not all positive or correct. Your job will first be to ask questions and listen. Ask about their concerns, their smoking habits, etc. Listen.
Lastly, be patient... remember, this is all new to them and smoking has been a lifelong habit for many. Your patience with potential customers will pay off in sales. And, no matter what you are selling.... always be honest, be realistic (under-promise and over- deliver), believe in what you are selling (it shows). Good luck.