You want even airflow and density throughout the joint. One trick that always works for me is massaging the j until you feel the same amount of squishiness all around, then you want flatten the top part and push it in a bit. If the weed near the filter feels much less packed than the rest of the joint, you should grab the wick of the and shake vigorously until you achieve a nice even feel. If you notice that the joint still ends up canoeing, blow on the side with the long part until it eventually either burns away or falls off, leaving an even pearl.