Over the years, I've observed that a lot of my beginner students don't take enough time to tune their guitars thoroughly. They tend to view the process as a nuisance and they blast through it as quick as possible so they can get on to actually playing, often leaving the guitar less than properly tuned. You might want to consider the fact that you're just working against yourself this way. Here's why.
It's much more FUN and SATISFYING to play a guitar that's properly tuned. That's just the way it is. Our modern guitars are very precise and well designed instruments. They are capable of producing the most incredibly sonorous tones ... but this will only occur if the guitar is brought into "focus" by tuning it with the precision it requires.
I think many beginner guitar students just can't tell what they're missing when they do a less-than-perfect job of tuning. They say "Sounds good to me" not realizing that a couple of more minutes tuning would have made the guitar sound that much better. On a subconscious level, your brain might be going "This doesn't sound as good as I want it to". I think many young guitarists then blame their PLAYING for the problem when it's simply a tuning issue. It wouldn't surprise me to find that certain aspiring guitar players have actually GIVEN UP the guitar for this reason! What a shame!
Back in the old days, we all had to tune our guitars by ear. This was problematic because beginners are rarely able to actually do that well. When I first started playing guitar, my ears were good enough to tell me that I was OUT of tune, but they weren't quite good enough to tell me what I had to do to CORRECT my tuning. I remember sometimes spending like 20 minutes trying to get the stupid guitar in tune ... by which time I was so frustrated, I didn't even want to play it anymore.
Nowadays, we have these wonderful electronic guitar tuners and I recommend that all of my guitar students get one. You can tune your guitar perfectly in like 30 seconds and go on to the joy of playing a properly tuned instrument. Some guitar lesson programs and teachers still contend that you should tune your guitar by ear ... but I disagree. All professional guitar players use tuners now. Why wouldn't you? It does a BETTER job in LESS TIME. Certainly you might want to EXPERIMENT with tuning your guitar by ear just to see what it's like ... in case your tuner dies in the middle of a gig. Otherwise, save yourself the hassle. Use a tuner.
Some folks contend that they can tune their guitar BETTER by ear. Indeed that might APPEARto be true in certain situations. But that's only an illusion in ways that are too complicated for me to explain (involving TEMPERAMENT) in this short post. I might actually contend that if you COULD tune your guitar better by ear, there might actually be SOMETHING WRONG with your guitar (poor INTONATION) and you might want to have your local guitar tech adjust your instrument.
Simply using a tuner doesn't guarantee that you'll tune your guitar perfectly. You have to use the tuner CORRECTLY. Pluck the strings the same way you would when you're actually playing ... not stronger or weaker. Dial it in as precisely as you possibly can. Take those extra few seconds. Don't be sloppy with it.
You'll need to go through the strings several times. You'll come to understand that the tuning of ONE string might ALTER THE TUNING OF YOUR OTHER 5 STRINGS (particularly on guitars that have a "floating" tremolo system). When you start over after finishingtuning your 6th string, you might notice that the first strings you tuned have gone back out again. I would suggest that you keep going through ALL your strings until you can go through them without having to make changes to ANY of them ... and this could be as many as say 10 times!
Also, tuning a guitar is a moment-by-moment thing. You really can't count on your guitar staying in tune for any significant period of time. Sometimes a new student will ask me "Why do I need to tune my guitar? You tuned it for me last week". I point out to them that their guitar probably went a little out of tune bouncing around in the car on the way home from their guitar lesson!
Your guitar strings are constantly stretching. The act of PLAYING the string can cause it to slip. Make sure your tuning machines, neck bolts and bridge parts are all correctly tightened down to keep them from moving around.
Certainly you want to tune up whenever you sit down to play your guitar, and I would recommend checking it every few minutes. When I'm performing, I check my tuning in between EACH SONG WE PLAY. I have a way to shut off my sound so that the audience can't hear me and I'll quickly check it while they're applauding and we're introducing the next tune.
There are many different tuners you could consider buying. I suggest you get a CHROMATIC tuner instead of a plain ol' GUITAR tuner. Chromatic tuners can tune all 12 notes which you will need when performing songs with ALTERED TUNINGS and these are more common than you might think.
Guitar tuners have different features that account for price differences. If you're performing AMPLIFIED, you might want a tuner that you can plug the guitar directly into. This bypasses the built-in microphone so the tuner won't be confused by other noise in the room. Many tuners also have an OUTPUT jack so you can connect a second cable out to your amp. This way you can simply leave it plugged into your signal chain the whole time. Your guitar plays right through the tuner into the amp.
Tuners with these features can be expensive. If you're looking for a nice little tuner to use at home, I recommend a KORG CA-30 CHROMATIC TUNER. These should be available at any reputable music store or online for about $20. Don't settle for less.
So tune that guitar correctly. It's worth the few extra minutes. You'll be rewarded with a much more satisfying musical experience. You'll thank yourself ... and so will your AUDIENCE! ;o)
All the best, Scotty West