Congratulations. I have a 1 year old daughter and I can tell you that the experience is unlike anything else you've ever gone through in your life.
My advice to you is this:

1. Complete any tasks or projects that you've wanted to do before the baby arrives. Realistically try to finish it before your wife reaches her 7th month of pregnancy.
2. Start to begin the mental transition into accepting that your needs are going to be on the backburner for a bit and you should expect to be inconvenienced often.
3. Embrace the suffering. If you're a good man you will try to lighten the burden of this new experience with your wife by sharing in the trying experiences such as getting less sleep, getting up in the night often and putting aside your personal plans/pleasures.
4. The most challenging aspect of having a newborn or a baby in general is the CONSTANT nature of it. I would gather that you've never experienced anything in your life that you've needed to tend to 24/7. You don't get a "break" and if you do get a temporary break, that responsibility will be right there waiting for you when you get back or the next morning.
5. Don't be too hard on yourself. While you want to do the best for them in all stages of life, understand that the main ingredient is that they are in a loving family that can provide them with time, attention, affection, and structure.