Quite a difficult topic, so I usually spend a lot of time on training "paraphrase" to get these participles -ing! Usually given as a hometask but can be exploited in any other way you will find suitable.
My students call me Miss TN (Tatiana -is my name; Nikolayevna -is my patronymic but TN is for short). I work with students (starting age 4,5 and the eldest students are over 50). Sometimes I have to be tough for the sake of the language environment that I desperately try to create.