Learn to read fluently. Music, that is. With the guitar, this means acquiring the skill to effortless sight read every note starting three spaces below the treble clef with the low E all the way up to the highest C on your fretboard. It also means fluency with tablature and the ability to instantly recognize chords. It is true that there are many examples of guitarists who never learned to read music. It can definitely be done. But my guess is that having come to the goal of learning to play later in life, you’re looking for the fastest, surest, most efficient way to learn. That path lies through reading fluency.
Mel Bay’s Modern Guitar Method Grade 1 is an excellent resource in this regard. The book is driven in part by a string by string, note by note acquisition of reading literacy. In the long run, if you follow this approach and learn to sight read, you’ll be further ahead than had you played by ear or learned only tablature notation. There’s also a dark side, so to speak, to skipping the literacy process. It is almost certain that if you stay with the guitar that at some point you will wish you had learned to read. This often happens to younger musicians who were trained to play by ear. The process of going back and learning to read after you can already play can be laborious and even downright painful. Another way to look at it is like this: I doubt anyone has ever said, “I’m sure glad I never learned to read music.”
And who knows? You may eventually want to write down songs of your own creation.
Good luck and keep practicing!