Tapping the person on the shoulder and waving from a distance are acceptable methods for getting the person's attention. Pause between subjects. Use keywords to introduce a new subject. Rephrase misunderstood sentences instead of merely repeating them. Do not be reluctant or embarrassed to use paper and pencil for communication if you can't understand your patron's request or it you can't make yourself understood.
Facial expressions are important clues to the hard of hearing person.
Feelings are more often expressed by non-verbal communication than through words. Stay positive and relaxed, do not become impatient.