Whenever you are using your brakes in the rain it is always important to remember that they could slip. What this means is that you should certainly increase the stopping distance between you and the car in front of you. You also want to make sure that you brake a lot earlier and with a lot less force so the car behind you knows exactly what you are doing.
The rain is something that will slow you down and you should certainly make sure that you allow a lot of travel time as you will be driving at a slower pace than you are normally used to. There will also be more traffic than what you are used to, so you want to make sure that you definitely allow yourself some more driving time.
One thing that you should take to heart is that you do not need to rush anywhere. You want to take it slow, that way you do not get into any accidents.