It doesn't really need deep study, just learn which verbs go with infinitives and which do not.

Read this and create:

let + object + infinitive

Like make, see and hear, let is followed by object + bare infinitive. It cannot be followed by verb-ing:

Let me carry that box of papers for you. It's very heavy.
Why don't you let him walk home by himself from school now? He's eleven years old after all.

Let is also frequently used in the expression let's (let us) to introduce a suggestion. Note that negative sentences with let's can be formed in two possible ways:

Let's finish the video tomorrow, shall we? I'm tired and I want to go to bed.
Let's not be late home tonight. It's Monday tomorrow after all.
Don't let's get too stressed about this. I know the car is damaged, but it's only a piece of metal.

We do not normally use let in the passive voice.