Twig I personally think Craft Fairs are good, for various reasons, not least you get to meet a lot of interesting people.
I have been doing Craft Fairs for 20+ years and average about 12 a year, some times more some times less.
Over the years I have discussed the virtue of doing CF with numerous Craftworkers and get a mixed reaction but generally those that do not make Big Sales on a regular bassis appear to disappear from the scene, one assumes they give up, whereas those that take the Highs and Lows are around year after year.
I have kept a record of everything I have ever sold and todate I have sold over 13.000 pieces from Lightpulls to Large Bowls and everything in between, this enables me to do two things, firstly it allows me to Turn and not fill our House or the House of Family and Friends with my Woodturning.
Secondly it finances not only the Raw Materials associated with Woodturning but also allows me to purchase new Tools and Equipment.
As I am not reliant on any income from CF for my day to day living the occasional Bad CF is not a real disaster.
I have based the success or failure of any CF on a ratio of 3 times the Stand Fee, loosely based on 33% for the Stand, 33% for Costs and 33% as Profit, it is meant as guide, if I achieve this or better I go home with a smile if not I rethink whether it is worth doing that CF again.
My records show that I have achieved this ratio for 75% of the Fairs I have done with the best 18x and the worst 0.2x, since 2004 only once have I failed to make my stand fee.
You will need Public Liability Insurance as a minimum, to a value of at least £5million if you intend doing larger CF, this will cost in the order of £50 but should you want to demonstrate it will be considerably more.
PAT Testing of all electrical items on your stand [typically Lighting] is required and many CF Organisers require a Risk Assessment for your Stand/Dispaly/Electrics Etc. Etc.
Payments are predominately Cash but a Credit Card facility will without doubt increase your sales, I have had a Credit Card option for 2 years and sales in those years have increased dramatically, there is of course an on cost with such a facility that eats into any profit. As an example today I did a CF and 53% of my sales were via CC.
Tax! do not try to hide any income from the Taxman, it can be expensive if you are caught out, it is not unknown for the IR to target CF.
The most important thing is to get the balance of what you have on offer, the majority of the things I make and sell are nothing like the things I had on display for my first show, you need to generate your own style, produce unique items and try not to copy other Woodturners work, the buying Public are a discerning lot.
Hope this helps and that you give it a go
Richard