Mistral sizing is, IME, true to 'reasonable' sizing - ie it isn't vanity sizing, but nor is it tiny.
So I have always, for 10+ years, gone to size 12 as the 'default' sizing in clothes - sometimes had to step down to a 10, in the early days when sizing was smaller up to a 14. In M&S I am now more often a 10 as their sizing has changed.
In Mistral almost everything I buy in a 12, although I do have one or two 10s. Trousers are quite long IME, a very few dresses are tightish across the shoulders, but generally true to size.