Use the Offset tool often. The offset tool in Photoshop allows you to offset the photo so that the edges appear in the middle of the frame, allowing you to see how the edges will line up if the texture is tiled in-game. Try to blend the edges into each other using the smudge and clone tools.From here.
Justin TimberlakeWhy rowley, why?!
Sophie Ellis-BextorWhy rowley, why?!