One of the main things you need to do when singlehanding, is to think through what you're preparing to do. Have a clear vision in your mind of what you need to do, and in what order you need to do it. You won't be perfect at first, but as sailingdog says, practice, does make perfect (or at least as perfect as you get sailing a boat).
What works for me is to loosen the jib
sheet and hold it in my hand, then turn into my tack. I then put my foot on the jib
sheet and take up the other one in my hand. As the jib
starts to backfill, I begin pulling in on it and straighten the rudder. Once the tack is complete, I then trim out the jib
. Unless I have the boom way out, I don't worry about it until the tack is complete.
As I said, this is what works for me. What works for you is something you have to figure out as you do it.