Telling someone what to do, formally, telling a group what to do, or suggesting doing something together, all three borrow their endings from the subjuntivo. Learn the pattern once, use it everywhere.
One person, in a formal or professional situation.
A group of people, two or more, formal or not.
A suggestion to do something together. Corresponds to "Let's" in English.
Ud., Uds., and nosotros commands are all built the same way, and they all use the same conjugations as the subjunctive.
Start with the present-tense yo form of the verb.
Drop the -o to get the command stem.
-ar verbs add -e endings. -er / -ir verbs add -a endings.
These five don't follow the drop-the-o rule, so they just have to be memorized.
Stem-changing -ar and -er verbs lose the stem change in the nosotros command.
-ir stem-changers keep a change in the nosotros command, e→i or o→u.
Every other verb uses the same base form for both affirmative and negative nosotros commands, just add no. Ir doesn't.
Read the subject and infinitive in [brackets], then type the matching command.
Same idea, but watch for the exceptions from the sections above.