"What are ways to introduce pronunication exercises in lessons?"
Teachers find it hard to integrate pronunciation into class. Reviewers complain that many books lack a consistent pronunciation syllabus. Pronunciation is a problematic area for many teachers, and when I was teaching for the RSA exams, phonology was the least popular topic. The committed have classrooms covered with phonetic charts, other teachers treat the problems as they appear. In global coursebooks, its difficult to establish a consistent approach to pronunciation. While Japanese students might benefit from work on l and r, Latin Americans would wonder what the problem was. Germans have awful problems with v and w. Most nationalities dont. For Arabs its b and p.
Varieties of English are another major difficulty. Too much effort is often paid to accurately repeating some supposed norm for pronouncing individual sounds. On vowel sounds the teacher model shifts dramatically, both depending on country of origin, and with native speakers, on region. I once saw a brilliant demo lesson on basic vowel sounds, observed by twenty or so teachers. As soon as the discussion started, the vowel sounds from Canadian, Irish, Scottish and Southern and Northern English teachers varied enormously. The intonation patterns of Welsh, Australian and Norfolk speakers failed to match the text at all. When we were working on The Wrong Trousers ELT adaptation, we planned a series of stress exercises. But Wallace has a Northern English accent and in a word like Birthday, he puts equal stress on birth and day (where RP British English would stress birth).
The textbook should expose students AND teachers to a whole variety of exercise types. Then the teacher has to decide which type to develop with their class. See which ones are beneficial, which are popular. There are times where pronunciation work naturally occurs (endings of regular verbs in the past).
Start by focussing on how pronunciation affects communication. I used to spend a lot of time in the first or second lesson teaching ways of saying Yes. It can be a question (Yes? = What can I do for you?), it can be a cheerful affirmative, it can show doubt (Yes = maybe). It can even mean no. e.g.
A: Do you like my new hairstyle?
It can mean (as it often does in Japan) I hear you which is confirming attentive listening, rather than affirming or agreeing. In fact research on business meetings indicate that the most common word for introducing a negative response is yes:
A: So I think we can double production
B: Yes. But
Then at least people get sensitized to the fact that intonation affects meaning. And you can go from there. How far you go is another question. For example, Japanese students can benefit by physical tongue exercises in front of a mirror. Actually physically moving the tongue daily helps with those English sounds, but its best taught on a one-to-one basis.
A word of warning. I have seen more student confusion and embarrassment caused by over-attention to pronunciation than I have by anything else. There are those who believe that students must perfect the sounds before progressing and those who believe students will slowly and gradually improve. I believe that a musical ear is the greatest factor in how well students pronounce English. In my travels I have met people with impeccable grammar, wide vocabulary and awful accents. I have also met people who speak a few words of English, but have a great accent. I think musical ear is the key. You cant actually teach this. You can improve sensitivity. You can try to eliminate confusion.
An anecdotal example. I lost a filling in a tooth at Barcelona airport on the way to a seminar. There was a pharmacy, and I asked for a temporary filling material. The assistant said, Sure, no problem with a confident voice (and slight American accent). Before applying it to my throbbing tooth, I sat down to test my Spanish guess rate on the instruction leaflet. It said that it was extremely dangerous to get it on your hands or skin, and to seek medical attention if you did. This cant be the right stuff to put in my teeth, I thought. So I went back to check. I then discovered that the assistant spoke about fifty words of English (if that), but had a great accent. Shed sold me some kind of superglue for repairing broken dentures. First, she must have had a great musical ear for language. Second, whoever taught her to pronounce that well did no one a service! It masked her inabilities in English. If she had had a strong Catalan accent, I would have assumed the possibility of crossed wires in communication!