Apart from the obvious, which is to tell your wife that you LOVE her.
I would also recommend that BEFORE the baby arrives cook up lots of nutritious meals that can be frozen in sealed microwaveable containers for the times when you will need them (trust me you will be needing them)! If you do not have a microwave all you need to do is to remember to take them out of the freezer to thaw out/defrost in time ready to eat.
You and your wife will both be sleep deprived and tired and you will not feel like cooking so having these frozen meals on hand is very handy and they will also help you save some money in the long run.
Being a parent is a wonderful thing but like everything the more you put into it the more you will reap the rewards.
I wish you and your wife all the best.