I also,recommend a good electronic tuner. If you buy one from a local music store, they should be able to show you how to use it. Some people can hear pitch well, and others cannot. I used to teach my guitar students how to tune to their piano, a guitar pitch pipe--I never found one less than a quarter of a tone off, or tune the guitar to itself. Only in recent years have most folks gone out for the electronic tuner, as they were made small & practible for easy use by ameteurs. Get one, and tune the strings beginning with the lowest: EADGBE