I can offer office policy on this, no better authority. (Full disclosure, I wrote the office policy myself.)
There are two choices. The basic difference is whether you want the list to be one long sentence, or whether you want each item in the list to be one or more sentences. But you must use complete sentences. And a sentence must not straddle only some of the list. A sentence must either be confined to a single list item or be the entire list.
Also, usually, a paragraph ends at the end of the list.
The first choice is to introduce with a full sentence ending with a period, then make each item in the list a full sentence ending with a period.
I like fruit.
- Apple is a kind of fruit.
- Banana is another kind of fruit.
- Cherry is a red kind of fruit.
- Date is a kind of fruit.
The second choice is to introduce with an introductory phrase and a colon. Then, each item in the list is expected to be fragment. The items each start with a capital letter. You put in commas after all but the last. The last gets a period. The second last gets a comma and the word and.
Here are some types of fruit:
- Cherries, and
If you find yourself putting in explanatory sentences in a list item, then you want the first choice.
If you are using a lot of bullet lists, especially if they begin to get very long, you should consider using tables instead.
The reason a sentence cannot straddle only part of a list is because it becomes very confusing as to whether the list items are divided by the part the sentence straddles or by the bullets.
Here are some kinds of fruit:
- Cherries are my favorite. And,
You see how confusing that is. Does this list indicate that apples, bananas, and cherries are my favorite? Or just cherries?