To express the idea of "let's" (a suggestion or proposal to carry out an action or participate in some activity together) Russian uses the imperative Давай (plural давайте).
Use it with the infinitive for imperfective verbs:
Use it with non-past "we"-form for perfective verbs:
The set expression «друг друга» is used to express the action done to "each other". The first "friend" is always in Nominative, and the second takes the case required by the sentence—and any prepositions you need:
To express doing an action together, Russian may opt to use words that specify the number of people as 2, 3 etc: вдвоём, втроём, вчетверо́м, впятеро́м, вшестеро́м, всемеро́м, also вдесятеро́м. Two to four are used the most. 8, 9 or larger than 10 are virtually never used.
English just uses "together", so, understandably, these are useful to know but boring to translate:
Bonus to those who speak languages that have similar adverbs.