Hammer nail through a wooden ruler. Hang picture on that nail. Line it on the wall where you want it. Remove picture, push in nail to make an indent. Remove ruler, hammer another nail into the wall Hang your perfect picture up.
How to Attach a Tube to the Kitchen Soap Dispenser - post shows how to attach a piece of tubing to a detergent bottle cap so it is securely attached. Bypassing the small detergent dispenser is a smart (Bottle Garden Life)