Do you think it is best to avoid errors in class?
No. I consider the mistake as a part of the learning process, I try to expose my students to enough examples to get a clear idea of the target languge. I enjoy a lot my classes when my students participate in all kind af activities trying to do their best effort to learn. So, When they have errors, I correct them in different ways and noticing the importance of making them.
Which of the previous ideas have you tried yourself?
Most of the times I write on board the common mistakes and ask for my students find and correct them.
I usually make gestures too when I listen a wrong word.
I always read my students´answers and when I find one I repeat the wrong word making a question, if they don´t get it the main mistake I explain again the target language, but with the inconvenient of having numerous groups , I do it in a whole group presentation.