My brother-in-law did web design for customers in the UK. He did it unofficially from home (now my Villa) but when he decided he wanted to do more work that got him out and about and that is where his problems started.
In Turkey there are a lot of very jealous locals who think that it is wrong for Brits to work there. The red tape by all accounts is an absolute minefield when everything goes your way but when there are lots of locals complaining it will make things 100 times worse.
My advice mirrors what you have heard on here already, don't bother.
I have worked in Brazil but again I wouldn't advise it. I found it very difficult even though I was very heavily supported by my company and I speak Spanish and can get by in Portugese.
If it isn't a silly question why don't you try Spain as a starting point. It's safe and a lot less beaurocratic and well tested by many a Brit. You can tour the areas staying around while you make up your mind where you like and then rent an apartment while you look at bars and restaurants. Never take an agent or current bar owners view on takings however. If you like the place then spend time in there at different times making a note of trade.
I remember meeting a couple in Majorca who sold up in Blighty, went over one weekend and bought the first place they were shown. They had dreams of a nice little English Cafe by the sea. The area was Playa De Palma, a predominantly German area. It closed within six months.
Clearly you are doing your research but if it is your first time working abroad then stick to what is safe and save Calis for holidays and retirement.
Pete