I’ll answer your question to the best of my ability; it’s actually difficult to give you a complete answer when I have so little information to go on.
The pronunciation problems encountered by learners of English depend very much on their mother tongue. For example, learners from some Asian countries have difficulty distinguishing between “l” and “r”, whereas for a French learner this is not a problem. I suggest you start with the seven words you have decided to present and consider whether your students will have problems with the sounds in those words; for example, Spanish students find it difficult to pronounce words beginning with “st”.
As I don’t know the nationality of your students, I’ve decided to focus on “h” because a large number of nationalities have problems with that sound. Direct the students' attention to the word “hello” and ask them to say it; insist on correct pronunciation especially pronunciation of the letter “h”. Explain to students that if they hold a hand in front of their mouths, and if they pronounce the word correctly, they will feel a slight breath on their hands. If the students are beginners, they won’t understand this; so, you will need to demonstrate it or explain it in their own language. Say the word and ask the students to listen to you. You can then ask them all to repeat after you. Then ask a few people to pronounce the word individually.
You can then do an activity involving what is called “minimal pairs”. Minimal pairs are two words that sound exactly the same except for one letter; e.g. hat / at; ham / am, hash / ash. I suggest that where possible you choose words that the students have already studied. If this isn’t possible, don’t worry because the pronunciation aspect is more important than the meaning of the words. Write the minimal pairs on the board in two lists: list 1 and list 2, as below:
Read the minimal pairs out slowly while the students listen. Then read out only one word and the students say whether it is in list 1 or list 2; this is to check whether they can hear a difference between the sounds. Hearing a difference is the first step to pronouncing correctly. When you think the students have understood; have them repeat words after you. You can then point to words and ask them to say them without giving the model yourself. Make sure you correct all pronunciation errors.
You can then ask students whether they know any other words that begin with “h”, you can write these on the board. You can then practise the pronunciation of those words as mentioned in the first activity.
Good luck with your lesson, I’m sure you’ll enjoy it.
If you’d like to write in again and give me information about the age, level and nationality of your students as well as an idea of the length of the class, I will be very happy to give you a more complete answer.