I have a Snark. Very accurate. Start with the high E. The Snark will be green when it's right. Not anything to the right or left. Exactly in the middle. Then just work your way up B, G, D, A, E. I have another guitar that I keep tuned down 1/2 step for a song I am working on called 'More than Words'. The Snark helps me keep it exact. Good luck.