Start your lesson with a light, easy, "colorful" activity to get the attention of the students before getting to the nitty-gritty of your lesson.
Quick rounds of conversation are always effective, but another idea is to give the students a visual prompt such as a picture, a piece of colored paper with vocabulary, suggestion, joke or other written prompt you may have to start the lesson. If all the colors are different, the students may think that each student has something different, creating curiosity. The handing out of something to each student is very inclusive and inviting. Each student knows that he or she will be expected to give some kind of answer or comment.
You can use this kind of warm up pre grammar, writing, reading or speaking classes.