The most common way to indicate a new speaker’s dialogue is to start a new paragraph.
Here is an example from my forthcoming novel, Touched:
Rashan slouched into a nearby folding chair, not bothering to get one for Georgia. He moved a few braids from his forehead, but they fell back over his eyes. After a silence, [...]

I am not sure why so many “Al” words, e.g., altogether vs. all together, alright vs. all right, already vs. all ready, cause so much confusion but here are two more pairs of “Al” words clarified for you.
Allot vs. A Lot
The word allot means to parcel out.
Example: The company will allot each of us a [...]

Rule 1: Use the colon after a complete sentence to introduce a list of items when introductory words such as namely, for example, or that is do not appear.
Examples:
You may be required to bring many items: sleeping bags, pans, and warm clothing.
I want the following items: butter, sugar, and flour.
I want an assistant who can [...]