Fortunately for you it is easier than several years ago when you had to depend on your skill and trained ear. Why? Because there are some tools now available to you so that you can start learning and training your ear, plus improving your knowledge of chords. Especially those strange 6ths, 7ths, suspended and Diminished chords you tend to avoid when choosing songs to play.
I've been there and most everyone else unless you are a natural talent who plays by ear exclusively like, say, Glen Campbell. OK, I'm old and you may not have heard of him. We all have our guitar heroes. Me included.
I would be remiss not to mention that creating a tab for yourself verses for this site is vastly different. There are rules to be adhered to. They have changed with time as all things do. That is why you may discover older tabs on the site are not formatted very neatly and may contain non-standard notations. Some may list all the lyrics but only steer you in a direction for the chord progressions. Let us hope you do understand chord progressions. If not, never fear, there are a wealth of online descriptions and sources.
It would behoove you to read and understand the sites rules for how to format your tab lest a moderator veto it or voting chaps hand you a rejection which will hurt your feelings the first time but I assure you that you will recover and edit the tab to perfection.
For your first tab I would strongly recommend a song you have mastered and are comfortable with. No one expects it to be just like a piece of sheet music out of a cheat book, in fact the site discourages that I think. Make it your interpretation. But it should be similar to the original lest someone tries to play along with it and gives your tab a bad rating. Surely you have determined what those yellow stars are by now, right? Oh yes, the site only likes 5 or so tabs of the same song unless you can provide insight as to why your tab is much better than the others. Don't let your ego get ahead of you on that one.
Songs have walk ups and walk downs, fills, sometimes added 7ths. A7 D7 G7 C7 E7 are some of the more popular. You can enhance a song with them as long as you don't go to extremes. Try to make sure the lyrics are correct. Don't depend on posted lyrics from the net, they are more often wrong than completely correct. Always listen along with an MP3 file to make sure they are correct. Always spell check and beware of the abbreviations like putting an apostrophe or single quote in place of the letter G when a word ends in "ing" i.e. breakin' or you can place it in front of a word like 'round (around) or 'cause (because). I'm sure you have the idea. Personally I don't use commas or question marks. I think they make the tab hard to read while playing along with it, but use your own judgement.
Should you have trouble finding lyrics posted on the net and have to rely on your own transcription, be careful of those hard to understand words. Try slowing the song down if you have that capability.
Sometimes speeding it up even helps to understand a word or phrase. There are programs that can isolate lyrics from the music, they really help. Sometimes you just have to look at what the song is saying and decide if what you hear makes sense. I have found that once you find the right word/words you will then hear them clearly in the song. Go figure, there's bound to be some study on that like not being able to see certain words in paragraphs...
So much for a song you know. What about a song you like but haven't played and for some reason there just isn't a tab for it anywhere or the ones you've tried to play are just so far off you can't play them.
First a note about MP3 files on the net. Upload and download speeds can vary the tuning of a song by as much as 25 cents (a term for pitch) I find 15 plus or minus is the norm. There are programs that will allow you to adjust for this. If you don't have one, try tuning your guitar to the song, flat or sharp. One things for sure, if you aren't in tune your task difficulty just increased by a factor of ten.
Determining the key your tab is in would be my first step. There's only 7 notes along with their sharps and flats (occasionally minors and the like) so trial and error will work for you. Once you know the key, look at some of the chord progressions for that key or if you know a little bit about the circle of 5ths, start there. If you don't know what I'm talking about, some of the more popular Guitar Chord sites have a function where you can enter the key and it will give you various chord progressions. Really helps in finding that chord that may be alluding your ear.
There are several programs available to you and some are free that can get you in the ball park for chords but they will never be 100%. You will have to try and find correct chords. Sometimes they may give you an Em but it will be an E chord, or they will show a Bm and it might be a B7. So you will have to feel around for the right chord. A search for that type program will yield you plenty of choices. I won't mention names here as I don't want to endorse one over the other. There are also programs that can slow down, loop, change pitch and even transpose for you. This site has a handy transpose feature that is very helpful. You will need to brush up on the use of capos.
Check out some of the transpose charts for capos if you don't know how to use them. I like this site's feature because when I play my Baritone guitar tuned to A I just have to click up or down a 5th (literally 5 clicks) and I have a Baritone Tab ready made for me!
When you format your tab with Intro, Verse, Chorus, Bridge, Pre-Chorus and Outro, leave enough space so it isn't jumbled together. As you determine your chords try to place them precisely where the change over is. Check out the rules for adding a lead riff with the fret board using dashes so you won't be rejected.
One thing to be careful of is song titles. MP3's aren't always titled correctly and it is always a good idea to add the name of the album if you can find it. Don't get carried away with too much information. Signing your tab is optional as the site will put your username at the top of each tab when posted.
Always play your song thru a few times to make sure it sounds correct. If you hear something that is not quite right, trust your ear and work to improve it. Remember that certain chords are very similar to one another and that just a 7th or minor 7th can make a great difference. Many times walk ups and walk downs will start with for example, C#m, then drop to a C#m7 or Bm will drop to Bm7.
Don't be afraid of the chords that are hard for you to play. By using them you will be surprised how quickly you will adapt to them and thus increase your range of playing. The barre chord is your friend. Chord changes are easier and much quicker. Example D# at the 6th fret quickly becomes Bb at the 6th fret. G# quickly becomes C#m etc.
When you post your tab be sure to complete all the required information asking about the tab. Sometimes after you type the title, the lyrics to the song will appear. Many times there are canned lyrics from the net and likewise are often in error by omitting words or having wrong words. I don't fully understand how or why the site does this. Just be aware of it because you can delete them before posting your tab or if you choose, use their lyrics and create your tab on the submission page. I find that creating my tabs on a notebook page and then just copy and paste works best for me. Be aware that at the bottom of the submission page is a block you can check if you want others to be able to edit your tab. Your choice.
As you start to tab your favorite songs, it is fun to check and see how many people have viewed it and liked it (sometimes dislike it). But be positive. Good things come to those who are patient. It's not uncommon for members to comment on your tabs.
As you post more songs you will acquire points and receive a ranking # which will give you and indication of how far you need to go to enter the top 100 list of contributors. If you are prolific at submitting tabs you may very well find yourself the top Contributor of the past month regardless of your ranking. Fun Stuff if you are on the competitive side. You will probably be at level I starting out or level II. After completing your profile, acquiring friends and posting more tabs, you will move up to level III. Then after having ten friends and five close friends along with tabs that are well viewed, you may achieve level IV. After that you may become a site Moderator.
Sometimes you may luck up and be the first one to post a tab that becomes very popular, say on the radio or videos, and you will be amazed at how many people will view your tab. Be patient exploring the site and you will discover all the little nuance's that take you to different parts of the site with all the information they contain.
This was meant to be a helpful primer to a beginner on the site and I hope it helps you getting started. If you have a question that an answer isn't readily available, ask someone who has a tab you like or try to locate a site moderator and ask them. They can be very helpful. You can always message me. Good Luck.