mrsparky has covered just about everything but there is another thing you can do to make accurate texturing a little easier using a layered painting program. If you make the background of the template layer transparent and then add that layer in-front-of your work-in-progress texture layer, then you will be able to see how the edges and features of your texture match up with the seam and grid guide-lines of the template. If you get this correct then it will look like the mesh grid has been drawn on top of your texture. Keep your texture layer selected when you do your drawing/painting and the template mesh will guide you. Then turn off the visibility of this top template layer (or delete it) before you do your final texture save. You will also notice that many textures overlap the edge of the templates, with a band of skin colour. This is sometimes necessary to prevent the appearance of ugly seams (white/background colour blended with skin tones at the edges of the textured areas) in the rendered texture.