Vocal Training

I'm no teacher but dont really believe that books can help every body. the way someone told me was just to practice breathing whilst singing ie sing a word & see how many seconds you can hold it for. take deeper breaths then too hold it longer or in different notes.sometims i record myself singing & then sing along to it & figure out what sounds better. i was also told if you have tried enough but still cannot hit the notes you cant force it just sing in a lower key or choose another song. i suppose practice makes perfect but then no one is perfect in my opinion apart from opera singers of course.