HI Fady, yes, I'm the same guy 
It's steveL not "1", but that's OK, and feel free to call me Steve here and at TGP in discussion
And thanks so much for your kind words!
I'm interested in how long you've been playing?
I've been playing for a very long time, so my process now has "matured" I suppose - in some ways I know a lot of crap already, so it's easier for me to just grab some things - like, for example, sometimes I'll hear a song in the car and I can tell from the sound of the chords what the chords actually are - I'll be like "C, Am, F, Em..." as the song is playing on the radio. Then I can go home and play it (if I remember it).
Though I can read music and could long time ago, I still find it FAR better to learn by ear.
I started by just trying to find the bass notes in pop songs - which often weren't all that elaborate (no inversions).
Later, I'd try to pick out notes on the higher strings (and still do) to get specific voicings and so on.
To some degree, I think learning like that - just sitting down with the radio every night and playing for hours on end - trying to figure out what I could (on the radio, so you only had one chance until you heard the song again!) both introduced me to a huge range of music and in essence forced me to practice working on my ear.
So to this day, that's my first line of approach.
But what I learned was, until I get the song in my head, even if I do figure it out in 5 minutes, I won't remember it the next day.
So now, if I'm learning a song for a band to play a gig that's a one-time deal, I'll often chart out the songs - basically they serve as "reminders" for me.
I generally tend to accept only gigs that I know the material for well by ear already - I mean, songs I've heard my whole life. For example, I've never actually learned to play "Tears of a Clown", but I've heard it enough times to know "how it goes".
As a counter example, I've tried to learn "Mr. Moto" - I did. Learned it note for note. I couldn't play it for you today if I tried. In fact, sitting here right now, I think the only thing I can tell you is the title of the song. I think - I think, it may be the same people who did "Squad Car", which I believe has a siren in it...
So if I were to take a gig playing "Mr. Moto", I'd have to re-learn it at this point. I just simply haven't listened to it enough to "have it in my head". I could learn it well enough in a week to read it from music, or from reminders I made myself, but I'd forget it in another week - because about all the time I spent on it was learning the song, and writing it out.
So it really helps me to really listen to the song a lot first (and continuously actually) to learn the song.
If a band calls me and says "we're playing "Pearl Necklace" by ZZTop, I'll be like "OK, I've heard it plenty, so I know how it goes" and can learn it pretty quickly - kind of because I know what to expect.
I've even been on stage and someone called a song (Blue Eyes Cryin in the Rain) and I played along on the spot - by ear - because having played enough songs like that, and having heard it enough times, I could basically "predict" what the changes were.
Now, if it was more complex, or jazz, or songs I was less familiar with, I couldn't have done that of course, but just being so familiar with it by ear, means I can learn it that much faster (again, whether I remember it a week later is a different issue...)
One thing that learning more by playing, and knowing theory (I took piano lessons as a kid, school band, then later guitar, then got a music degree) did for me was cut down on "trial and error" time - for example, if you know something is in A, you're less likely to try out chords with a Bb in them and more likely to think the chord is either A, D, or E, or possibly F#m, etc. And being able to hear the difference between major and minor also cuts down on that time even more.
I still get stumped by "odd" chords or uncommon chords, but I'll just slow down the music in an app and figure it out. Lately, because video lessons abound, I'll learn things from them instead, especially if I'm in a time crunch - I have no shame of using those shortcuts - videos, tabs, etc.
However, I would strongly recommend learning things by ear as much as possible (and of course, learning as much about theory and music in general as you can). The act of "figuring things out" both gives you a sense of accomplishment when you do, and seems to make them stick with you longer.
So now, my process can vary depending on the type of gig, type of material, how much time I have to prepare, and so on, but generally speaking - "get it in my head" aurally first, then start working it out bit-by-bit. If time is short, I'll "cheat" and use tabs or vids, or worst case, make up something to get me through the gig (also an important skill). But if it's something I really want to learn and have the time, I'll slow it down and learn it by ear - down to a single note repeated until I can figure it out - because as you know, sometimes the tabs and vids are wrong!!!!
May Birthdays 
