give me ur advice and tips please

My son just turned four and we will be having his baby sister in September.. I am kind of nervous to the whole thing and not sure how things are going to go or what I can do to make it go better? Was curious if anyone had advice or tips on things that they did? 
Ps. I will be having a c section and I'm also nervous about that and having to take care of them both during the day right after we have her.