just (do something)

You use this phrase when the action you're describing seems easy, simple, fast, unimportant, or unexciting:

I just googled "new york florist" and that was the first shop that came up, so I called them.

A: What did you do this weekend?

B: I just sat at home and watched T.V.

let's not (do something)

When you want to suggest that people in a group not do something, you can say "let's not ___". For example:

Let's not go out tonight.

You can use "Let's not ___" when you're suggesting something that you're sure the listener will agree with. In the example above, you think that everyone will agree that it's a good idea not to cook.

not bother (doing something)

The phrase "not bother ___ing" means to not do something that isn't needed. For example:

Don't bother washing those — I'll put them in the dish washer later.

I don't bother shaving on the weekend unless I have to go out to meet with someone.