ok, so really I'm the type of guitar player who works with rock and metal type stuff. But really this advice can go for anyone.
When getting a guitar, don't just buy anything.
Now I'm not telling you to get yourself a $5000 Gibson Les Paul, new guitarists don't always have the funds for such (I've played guitar for 5 years and I'm still waiting on getting a Gibson!). I mean if you DO have the money for it and plan on getting that, well good for you. But cheap or not, acoustic or electric, not all guitars are the same. There are ones that are made from different materials and woods. They all contribute in the sound. This is the same with amps if you plan on getting an electric guitar. Material doesn't matter much, but different amps come with different settings and what not.
For many, it is easier to just start off with an acoustic. I did, and I'm glad I did.
Being a guitar virgin will make your first time hurt.
Yup, go ahead and laugh at how I worded that. But its true! First few times you try to practice, its going to hurt your fingers pretty bad. There have been a few times in my life where I practiced too excessively with new fingers to the point where I got one of my fingers bloody. Even once had a blister too. But I saw it as a badge of honor, haha. Anyway, there are ways to try and lessen the pain a little. I suggest using nylon strings to start off with, then go with what's usually used. unfortunately for me I never even used nylon because every time I tried to put them on the guitar, it would snap out! even my dad tried. But don't worry, your chance of this dilemma happening is a bit less. Just be pretty careful with tuning the strings. There are also many other types of strings out there. Coated, uncoated, different gauges, etc..
And though it'll hurt for a while to play, practice is important! If you keep practicing, over time your fingertips will harden up and it won't hurt to play your guitar. Also, with whatever string you press down on, you can try to press it closer to the fret bars. It definitely hurts less that way.
Female guitarist wannabes, say goodbye to nice looking nails.
Really this part could depend on what type of guitar playing you want to do. I do mainly the aggressive type, so really if I do paint my nails, it won't be long before the paint starts coming off. Really I don't care about it that much but I know some other girls out there do. And really for anyone who plays guitar, ya gotta keep them nails short. Since you are pressing down on strings with your fingertips, your nails won't be in the way if you have them short. Plus you won't scratch up your fretboard. There have been a few times where I get a little lazy with keeping my nails trimmed, and I end up regretting it because I got claws that have left some scratches on my fretboard. Believe me you don't want that.
Now I know that there are some guitar players out there who use their fingers differently, where they don't totally use the tips, they just lay their fingers on the strings. Dolly Parton is a prime example of that, especially since she always has her nails long. Really most guitar players say that its best to use your fingertips, and I do agree with that, but it never hurts to experiment.
Learning guitar is both easy and hard.
I know this can vary among some people. But for many, it can be pretty crazy. This is what I usually tell people who come to me asking how hard it is to learn: It has its ups and downs. You can start off where it feels like everything is easy, but it'll get harder, then sometimes get easier, then harder again. And so on. Probably if you find an awesome guitar lesson series online it can help with this dilemma. For me personally, it got more difficult than easy for a long time. But it did get better the more I practiced. I used a lot of guitar lessons online, especially youtube. Which carries on to the next thing..
Beware of bad lessons on youtube.
If you want to use guitar lessons on youtube to help you on your musical path, well good for you. However beware of people on there who don't know what they are doing. I've fallen in their traps before. There are videos out there from people who film straight from their computer room, and some really do know their stuff. But it is also best to find videos on youtube from people who also have special websites for guitar lessons. I suggest for you to check out ones from YourGuitarSage and Ultimate Guitar as a few good examples.
When first learning...
Get to know your guitar. You got the headstock at the top, with the tuning pegs for the strings. You got the neck, the frets, then the body. Think of it like a person, since it literally has a head, neck and body. For acoustic guitars, there's the sound hole that amplifies the sound of the strings. It amplifies sound through vibration inside the guitar. Electric guitars don't have the sound hole since its not needed. Its just the work of electricity through pickups and your amplifier. Electric guitars and amps also have extra effects to add to the sound.
But before anything else, you need to understand how sound changes depending on each string and fret. Right here now you'll learn a little more from me.
So technically, the thickest string at the top is actually considered the bottom string, due to its sound. The thicker the string, the deeper and heavier the sound is. The top string is the thinnest. All 6 strings are named by just a letter. From thickest to thinnest strings, the names are E A D G B E. Wanna know an easy way to remember this? Just remember this sentence below, it includes all the letters!
As for the frets, if you play one after the other, going from the headstock to the soundhole/pickups, the sound will get lighter, more "bright". If you go the opposite way, it gets a more dark sound.
Learn the chords
Chords are a group of notes put together to make a sound. What's more difficult about learning chords is remembering the names. And of course switching where you place your fingers when playing more than one chord. I suggest first learning chords that use less fingers. They are easier. And remember, you really don't need to try to memorize every chord in existence. Why? There's hundreds of them! Too much to remember! There are many bands out there that use small amounts of chords. AC/DC is a perfect example of that. Many songs of theirs use just 3 chords. So really if you learn just a few, you can already do a lot. That was a band I started off with when it came to learning how to play songs, since they don't indulge in a ton of chords. Which takes me to the next thing..
Practice along with songs.
Once you get the hang of things some, you can practice along with songs you like. I don't suggest automatically practicing by ear right away. Go on a website (such as songsterr) to look up the chords to a song you want to learn. That website also can play the song at the same time as you look at the chords. You can also read the tabs, but sometimes that's more difficult to learn than reading a chord chart.
Once you learn a few songs and you're doing pretty well, your ears will be more sharpened to recognize what's being used in a song when you hear it. That is a better time to practice to it by ear if you choose to. Know that you may not always be spot - on with playing along, but it doesn't matter. You're practicing, not playing in front of a crowd.
And with songs that you use, don't automatically start off with crazy speedmetal stuff. Start off with easier stuff to go along with. Over time as you get better you can get crazier if you want.
Learn the ways of picking, using fingers and more.
Sometimes acoustic guitar players tend to use their fingers more for picking individual strings. That's a hard one. Also hard when doing it with a guitar pick. But when you get more experienced with guitar playing, don't be afraid to try it. Hardcore guitar players like me use alternate ways of picking and palm muting. Guitar slides are awesome, but don't be fooled! They look easy but are pretty strange things. Slides are especially used in blues guitar. You put one over a finger (I usually use my middle finger) and move it across the strings as you strum or pluck. Even if you don't have a slide, just get something rounded and move it across your strings to at least see how the sound is made. Slides usually come in a variety of materials and textures to make certain sound.
Have fun with it!
That's a given right there. But really, whenever times come where something becomes difficult to learn or practice, don't give up! The more you practice the better you become. Believe me, once you know the ways of guitar, it makes you view music in a whole other perspective that not everyone sees. It is quite an amazing thing.
And remember to take good care of the instrument. After playing, wipe it down with a cloth so that sweat and dust does not mess with the finish. Keep the guitar in a good case or gig bag when you aren't using it. And try to have it in a place where temperature doesn't fluctuate rapidly. Temperature fluctuation affects the strings.
Let me know if you got a question or two about guitar playing. I'm happy to answer it all.