Breaking in a pipe consists of smoking out any residues left in the wood after curing and building a "cake" inside the bowl of the pipe which helps the pipe to absorb moisture and heat. It is best to try to establish a cake in the bottom of the pipe first and gradually build it on up to the top.  To do so, load a pipe half full the first few times you smoke it and try to smoke it all the way down (when you suck a mouth full of hot ash through the stem you've gone too far).  After the first dozen or so smokes load it two thirds full and smoke it like that for a while.  Eventually, start loading it all the way to the top but still try to smoke it all the way down.  Once a cake has been established, the pipe will smoke cooler and stay lit easier.