 Drive it tight to the building. You're supposed to let that siding breathe or move a little bit because vinyl has a very high expansion ratio. So when the sun hits it, especially the sides of your house that are on the south side and the west side, when the sun hits that, if the siding's on too tight, it's going to buckle and get real wavy and ugly looking. There is no easy fix for this short of taking the siding off and then reinstalling it with proper looseness to each piece.