With the first markets under my belt here's what I learned;
1) Location Location Location! Get in early with the organisers and get a good location
2) Have at least 3 changes of $50 I only had a float of $90 in various notes and coins and needed to get more change of $50's early on. I also told someone I didn't have change of $50 and lost the sale.
3) Introduce yourself to the stall keepers next to you, its great for atmosphere but also if you need to nip into the loo they can keep and eye on your stall for you.
4) Do a practise run of the table set up before hand so that you can do it quickly and confidently on the day.
5) Make your table display appealing to the audience you are trying to attract. For me it is mainly mothers I want at my table so I had a really kid friendly colourful table with lots of lollies and sweets.
More on the display as it is the most important tip I have - do some online research there are plenty of sites with market displays. be individual, quirky, creative and make sure once its set up you stand back and look at it from the front.
6) Have plastic tubs organised I had one for my table display that had all the table clothes, table signs, chalk, plastic bags, packaging etc in it. I also have plastic tubs for my stock so its easy to pack and unpack. Also these make great little benches under the stall table so you can keep things on them.
7) Scope out the markets first well to understand if your product is viable there. In my case my instinct was telling me people don't go to the market to buy party goods and they might only have a $30~$50 total spend budget in fact i would think most people don't plan to spend anything at all and its all impulse buys. So what I decided to do was sell sweets and in doing so attract lots of people to my stall so I could then talk to them about my party products and give them a business card. I'm essentially using the market as a platform to spread the word.
8) Have all your stock priced, its also a good idea to have signs so that people that don't plan to stop and look can quickly see what you have and how much it is - this will encourage them to stop.
9) This one seems obvious but be friendly, smile and chat
10) Have fun