The following paragraphs represent weak and strong examples of coherence. You can implement them by having your students read them and asking them which they like better and why.
Weak Example: For me, the worst thing about waiting tables is the uniform. All the waitresses had to wear this ugly brown striped jumper. The shirts were polyester. Sometimes someone you know comes in. Now I have a job in an office.
Strong Example: For me, the worst thing about waiting tables was the uniform. At the last place I worked, all the waitresses had to wear an ugly brown striped jumper. Underneath it we had to wear an even uglier polyester shirt. Sometimes someone I knew would come in and I'd feel embarrassed by my outfit. Now I have a job in an office, where I can wear my own clothes.