Rule: And is the weakest conjunction; use one that better shows the relationship between the elements of your sentence. As with “to be,” you should note that there are many ways to connect your ideas. You can use other conjunctions; you can subordinate; you can string ideas together with semicolons (as we’re doing). And gives the reader two ideas and says, “Here they are, equal in all ways, neither one better nor more interesting than the other.” Make a bold value judgment to improve your sentence.
Note: Sometimes and works best to join two simple nouns or pronouns.
Examples:
Weak: I go to the store and I buy bread.
Better: I go to the store because I need to buy bread.
Weak: Zhang Min walks the dog and looks at the campus.
Better: While Zhang Min walks the dog, she looks around campus.
Practice connecting ideas in more interesting ways:
August and Citizen built a fort under the loft, and they played there for hours.
Melony destroyed the cabin and got mad at Homer for leaving the orphanage.
Strayed had made a shambles of her life and she changed her name and started hiking.
Resources for further explanation of strong ways to combine ideas:
Helping Writers Become Authors' Weak Conjunctions
English Grammar 101's Subordinating Conjunctions