Breath out on the Hard Part and Breath in on the Easy Part.
Breath out on the Concentric and Breath in on the Essentric.
Breath out on the Positive and Breath in on the Negative.
Example:
If your doing squats, you breath in when you go down & breath out as you go up.
Breathing is pretty important actually, from what I have found.
Practise what you Preach (I do

)
P.S, Nice to meet you Ironreps.. I see you around alot.
I have seen your log and your progressing well "hi-five".
Glad to have you here with us and not the brainwashed.