If you aren't painting over the skirting you will never get an invisible join and so it is best to try and put it in a position where it will be less noticable. Assuming you are painting them you should cut both pieces vertically at 45 degrees and then nail through both pieces when fitting.
then fill the nail heads and join, sand and paint as usual.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!