I usually warm-up with a slow-blues I found in a magazine years ago.
Here's a video .
Can't really notate more, because it's never the same after this.
It's pretty easy to change the drone to A for the second verse and then pop a B7 and do a lick to turn it around.
It's really hard to make your fingers slow down for this.
But it really sounds nice slow and sweet , too.
But it's so simple that the temptation to jazz it up can be irresistible.
Illustration made with MuseScore.
(Haven't figured out how to make the title smaller, yet.)
music.stackexchange.com/users/1344/luser droog
My favourite one because it really helps to warm up fingers.
Play the first bar and then simply go one string down.
Do this until you reach the last string.
music.stackexchange.com/users/3551/Max Malysh
Beginner here, I also warm up with blues, I am not sure about how to name what I play but it looks like that
(I copied the notes from a 12 bar progression): E|---------------- B|----------------
G|---------25---47
D|----25-26---48-- A|--26
--2----4-
---
E|-3--------------
I do it because my left hand needs to move vertically and horizontally
(which is the hardest for me right now).
music.stackexchange.com/users/3387/Learning is a mess
This is a good warm-up exercise to improve your finger dexterity on one string.
The jumps from the 4th finger to your 1st are particularly tough.
Follow the fingering guide above: 1 2 3 2 3 4 1 2 3 2 3 4E|--1-2-3-2-3-4-|-3-4-5-4-5-6-| ...
music.stackexchange.com/users/1379/Craig Curtis
Thats my warmups (first similar to Craig Curtis's).
But they're little harder, and can be used also as an exercise, not only as warmup.
Second one is about right-hand picking, and holding barre-chords.
music.stackexchange.com/users/2963/Jack L.
I usually warm up playing scales.
Sometimes I play a single major scale form in a cycle of fifths.
Other times I will just play through major and pentatonic scale forms in one key up and down the neck.
Then I usually just noodle around on some phrase or song with which I'm familiar.
Caveat:
I'm an amateur and have no sound reason for why this is good.
It just works for me.
music.stackexchange.com/users/5800/vantelimus
In addition to the examples shown here, I would advise you to warmup without the guitar, stretching your hands, wrist and shoulders, but also and in my opinion more importantly, to warm DOWN after a big session of playing.
I used to hurt myself when I was a beginner, as my left wrist would go from "inside" flexion during hours to a sudden outside flexion.
The content of the exercise itself is not that important, and chromatisms are quite boring and frankly quasi-useless as a guitarist.
What is important is to start slow, simple, with some are of your guitar playing which is mastered.
It might be simple chords, it might be polyphonic tapping or tremolo, it depends on your personnal practice.
A good video description of hand stretching
music.stackexchange.com/users/5937/Chipsgoumerde
I use arpeggios: major 7, minor 7, and dominant 7 in 5 positions (essentially CAGED).
Go through the circle of fifths, playing major 7ths in one of the 5 positions; repeat for other positions; repeat for minor 7 and dominant 7.
Practice with a metronome, and gradually increase speed (over weeks/months/years).
At the moment, I'm also working on tremolo picking, playing a scale using 4 sixteenth notes per degree of the scale (also, of course, with a metronome).
music.stackexchange.com/users/861/PSU
I saw some really good answers
and I agree with some of them.
My favorite warm up practice helps strengthen all my fret hand fingers, as well as providing coordination with pick hand and fret hand.
Starting on the low E string 2 - 3 - 4 - 5 then the A 2 - 3 - 4 - 5 then
the D 2 - 3 - 4 - 5 continue through all six strings and back up again.
Next move up one fret, so... 3 - 4 - 5 - 6 , then another fret 4 - 5 - 6 - 7 , all the way to 12 - 13 - 14 - 15 and back down 15 - 14 - 13 - 12.
This can be boring for your picking hand, so try all down strokes, or all up strokes, or alternate picking ( down - up - down - up ).
When I first learned this technique, I had a hard time getting clean sounding notes out of my pinkie ( since I used it so little ).
Then speeding up was tricky, but this exercise pays off!
One last thing I can recommend, is alternate the order your four fret fingers ascend and descend.
For example: ......2 - 3 - 4 - 5 then 3 - 4 - 5 - 2 then 4 - 5 - 2 - 3 last 5 - 4 - 3 - 2 This helps train each of your fret fingers to work independently and quickly.
Try it and you may find a fun new exercise.
music.stackexchange.com/users/6288/oneagent
This warm up exercise helps stretch your fretting hand.
I found a picture that explains http://www.fretjam.com/image-files/hand-stretch3.jpg Push as far as you can and use all three crooks of fingers.
music.stackexchange.com/users/6288/oneagent
I do not generally warm up, but then I don't really stretch my playing as much as my ear when I practice. But I know I should.  What are some good exercises to do before I start getting into the details of working for speed, developing scales, etc.?
What are good warm-up exercises for guitarists?
music.stackexchange.com
<guitar><practice><warm-up>
music.stackexchange.com/questions/9669
music.stackexchange.com/users/195/Dave Jacoby
Playing scales, simple chords, arpeggios and practicing with the metronome are all recommended warm-up exercises for guitarists. In addition, it is advisable to do some exercises for hands, wrists and shoulders before starting. To warm up before playing guitar, any kind of playing could be acceptable. However, scales and arpeggios are normally a good start, and you may want to use a metronome to build up speed. Another thing you may want to consider is stretching without the guitar first before you start playing.
You could warm up simply by playing scales. Any form of playing could be considered enough for a warm-up. You could try playing arpeggios to warm up. You might want to consider practising with a metronome to build up speed. You may want to warm up without the guitar first, stretching your hands and fingers.