What’s the most efficient method to try and guess a wallet’s private key?

I have a Bitcoin address that I want to guess its private key.

What’s the most efficient way to do it?

I don’t mean “use a trillion servers” but “use this program this way”.

Note that it has to run on windows.

I know that it’s pretty much impossible for a PC to guess a private key (more possibilities than atoms in the universe and all that) but still, it could be the very first key I try.