Yoghurt is easy to make.
You need milk, milk powder and a culture. My culture is four months old, and it came from a tub of yoghurt that I got from the cheese factory at Bodalla, NSW.
You need a plain unsweetened culture.
Many many years ago I purchased an Easiyo Yoghurt Maker, and I used it for awhile. But I never liked the yoghurt. I now believe it was the milk that I was using. I use a local milk that is the only one that seems to agree with me. So I do recommend you buy organic full cream, full fat milk.
So I stopped making yoghurt and eating it for a very long time. Last October I thought I would try it again, and well here I am writing about. I make a big batch every time. It does not last very long at all.
I have read about people using glass jars in the esky ( insulated container) to set their yoghurts. It would be something you would need to experiment with.
To start use a good quality culture from your dairy cabinet at your local whole foods store or health food or markets. Use an unsweetened, with no additives and preservatives to get the best result.