The only thing essential to salvation or for salvation is God's decision to save. I guess you could add that God has given us so much freedom that we could choose not to be saved, and therefore by choice, be unsaved from sin and its consequences here and now, then and there.
If you want to add, what can we do for this? The answer is: Nothing.
Now, we can go ahead and ask this question: What does God ask of us? That can be summed up with this: Love God and love people. In fact, so dedicated is God to this "love God; love people," theology, that Jesus said it summed up the law and the prophets. If that sums up the law and the prophets, then what else is there?
Yes, I know there are lots of commands and directives and so forth, but isn't that all in the details? Jesus did not abolist the law and the prophets, he fulfilled them. If I love God, then I am going to listen to Him. I love my wife and I listen to her. I love my kids and I listen to them. If I love God and listen to Him, then I am going to take what He has to say seriously. When I take what He has to say seriously, and what He says is to be baptized (the link to salvation in my fellowship), what motive would I have to avoid this act? However, to say that this specific obedience is the salvationary link smacks of worshipping baptism over worshipping the God of baptism.
When we get the focus messed up, we get into trouble - and fast! It's like this:
What do I have to do to be saved is not very romantic. It is not what a comfortable person asks. It is what a desperate person asks. We Christians spend too much energy trying to convince people that they are desperate, but we come across as arrogant, self-righteous, and elitist. Jesus didn't have to convince anyone he or she was desperate - check that, he pounded on the Pharisees about their desperation in the context of their feeling superior, comfortable and in control.
Why do so many Christians treat the "lost" like Jesus treated the Pharisees?
I think we're putting the wrong people in checkmate.