Its about the notes..

I understand the piano notation, but guitar has got repleating notes, like E string sound same on B string fifth griff (E also)..

If i play by notes, i choose my own positions for fingers? Same with other stringed instruments, right?

There is a lot of classical guitar tablature (as opposed to traditional notation) that contains numbering for the fingering. It specifies exactly what fingering is recommended.
As for other stringed instruments, such as violin, to the best of my knowledge they only use traditional notation which does not specify fingering.

Okay.

Thanks for your reply

Scales, exercises and studies help the player to choose the best fingering. That's not always the easiest. In classical guitar, a basic early principle is to choose the fingering which requires the least movement. More advanced playing includes consideration of tone: the same note sounds different on different strings.

__________________
"Music is a social act of communication among people, a gesture of friendship, the strongest there is."
- Malcolm Arnold.

Tab is the bingo of guitar playing in my opinion.
It saves players having to think about what they are playing.

Sadly because regular formal music lessons in schools in the UK are pretty much a dead duck now, nobody much gets that grounding in conventional notation like they used to, so the grass roots music thing gets picked up off the internet and there are more tabbers than there are notators evidently.
So now it is a sself-perpetuating thing.

I have to confess I cannot play from tab because I have the regular notation ingrained in my brain too well, but stumbling through a couple of Nirvana pieces with a pupil it occurred to me that there is just as much information missing in terms of playing technique & fingering as there is in regular notation, so there really isn`t any advantage to tab as far as I can see.

Thinking about you have written Mr. Terrible, it's really bad to think about the guitar fingerboard with numbers than with notes. I think standard notation should be practised and heard with ears and intellect.
About the fingerings on the guitar I find it pretty intuitive. Mark said it all. I'm still on the part of "the fingering which requires the least movement", which sometimes does not give you the best tone...I think

The worst part for me is seeing the number of relatively new players who, having picked up tab, play in a vertical manner sliding a finger up and down the neck instead of playing across the neck.
Surely the whole point of tab is to give at least an indication as to where you should be playing on the neck, if not giving the precise fingering to use?

Not sure "wrong" fingering will affect tone.
Fingering really is more about comfort awhich leads in turn to greater dexterity, but good tone is another thing.

One of the hardest things I find to teach my lot is that a note should consist of a beginning, a middle and an end.
This is less critical for guitarists than bassists in the popular music arena, but still essential for anyone who wants to produce good tone.
You might want to do a few basic vibrato exercises when you warm up - gets your hand/fingers used to the movements required to get good tone.
Are you playing steel or nylon?

I play both, classical and electric guitar. My classical is an Admira Paloma and has nylon strings. It has a warm sound, but sometimes I think the basses vibrate too much.
Really, when I think about fingerings, I think about the easiest way to reach the next note. At first one may seem the hardest fingering but when you practice you see that becomes easy and fluid. I'm talking about barre chords for example. Right now I'm learning Chôros Nº 1 from Heitor Villa-Lobos, and it's been very difficult to me because it's a challenge about fingerings. They need to be performed correctly and quickly. It's a easy way to loose your sanity.

"One of the hardest things I find to teach my lot is that a note should consist of a beginning, a middle and an end."
I think the first time I noticed it, it was when I was listening to Rostropovich's kind of playing. I found myself wondering "I'm figuring all the notes by itself, they're all coming to my ear and making an absolute sense, all the notes are respected", not because of the score but because of his soul, or sensibility, or whatever I cannot explain.

You might want to try a higher tension string set to control the bottom end.
If you find that makes the top 3 too resilient you can always buy a set of each and donate the ones you don`t use to people with weak fingers!

Seriously , Villa Lobos will make you think carefully about wrist placement too.
Always difficult to get smooth when moving through the positions, but with patience and good technique it WILL come.
And like I said, slow and right beats fast and wrong.

My typing is a good example of the latter(grin)