One might argue that being a Demo Artist/Brand Rep is an illegitimate job for 'real artists'. This is not the thread to make such an argument. I don't want to hear it and that's not what I'm asking.

I'm interested to know, from those of us who DO need to work while we're trying to building our portfolio, what helps your success in the sales department?  I just made the switch from full-time employment at Sephora to working as a part-time demo for a couple companies, and part time at a Shoppers Drug Mart Beauty Boutique (for those not in Canada, it's like a pharmacy/grocery store hybrid that also has a high-end make-up section.)
Demo work has turned out to be WAY harder that I thought it would be.  I hardly ever find myself reaching my sales targets.  At Sephora, it was never an issue, we didn't have sales targets or commission.

I'd love to hear advice from anyone who excels in sales.  I see some demo artists doing extremely well, and I want to know their tips, tricks, and secrets!

Good customer service is always key. Being friendly, always wearing a smile, and giving honest advice using your own personal experiences and tips related to the brand helps alot. Demos/promos that allow sampling are always the best. As a customer myself, not to mention the economy being what it is, it always helps to be able to sample the product before buying it...especially make up ( trying before buying). Make sure you mention any sales or coupons available.

I am in the same boat as you. Working part time in a beauty boutique, as well as being a demo rep.
From my experience, every client in your seat or person who walks up to you is a sale. It's all about knowing your product and engaging the client.
Compliment them and start a conversation. Always have a smile and be welcoming. Even if they don't buy that day, educate them, write down the product, let them know who the counter manager is. This way they feel comfortable to come back. Always let them leave with a positive experience.
I always give mini eye massages to each person who walks by, and 75% of the time, I sell one thing or another.

Hope this helps It's all about confidence, knowledge and smiling The more product knowledge you know, the more likely you are to sell. That goes for working in the boutique as well.