A very effective tip for teachers of English. 

With learners of all levels including sometimes the most advanced, I often come across the situation where the word ending ...ly is not used, or over used. 

When this happens I have a little visual trick which I can use to help the student with this problem. I avoid explaining any grammar, I simply draw a snail and an arrow.

 

To be honest the snail is not always as well drawn as the one above. Here is a real drawing made on my note pad during an actual lesson.

 

First I point to the snail and ask if the snail is fast or slow.

The answer is of course always given correctly as slow. Then I point to the arrow and ask how the snail moves. With a little help every student can get to the answer of slowly without me having to give them the word.

Then we go back to whatever their problem sentence was and they try again, almost always with success.