Hello!

I have a lemon tree which is 4 years old and would like to make a bonsai from it.

Looks like it doesn't feel very well because the leaves are a little bit dry and yellow.
How should i prepare the tree before cutting and placing it to a smaller pot?

Thanks in advance.

It needs a bigger pot and it needs to be out not in if it a Lemon. It is lacking in light and probably some nutrients

You simply don't make a bonsai out of a sick tree.