When you begin to enjoy playing the guitar and you feel like treating yourself to a new set of strings, it is very disappointing when you are expecting to enjoy the new crisp sound but it's difficult with your guitar strings going out of tune after a couple of strums.
Here is a quick hint to hopefully iron out the problem every time you change strings.
I had previously heard the phrase 'tune up to the note' before but never really thought about it too much and didn't know how it would affect me and my guitar.
Now, over the years, I have found some guitars are more sensitive than others with this, but when you tune in the guitar and go too high past the note, you would automatically tune down until you hit the note.
 There shouldn't be anything wrong with this, but this is not the best way to keep the tension in the string.
 You should slacken the string again and always tune UP to the note.
This has more to do with the tension in the machine heads / tuning heads and the more expensive or better quality they are, the less you should experience the problem.
This is a very simple solution and when I have used this method when tuning in someone else's guitar which might not be the best quality, the owner has commented on how quickly I have managed to get the guitar in tune and it will be partly down to this technique.
It's a good habit that to get into as the principle applies to every guitar which should help stop your guitar strings going out of tune in the future.