well i wanted to learn some singing few time ago already but i never really knew where to start and as im not planning to do it professional, neither joining a band (yet) i thought i'd just start off in here and try to get some tips about:

-what to do first (preparations etc)
-how to breath (explained for someone who never learned how to properly sing/breathe)
-how to put out vocals (mostly metal vocals but not growling only, i can do that specific stuff afterwards)
-what songs/pieces to try out first
-how to get feedback when youre just trying it by yourself( how do you know that you improve)

yeah and as a final question, i never really considered myself as a good singer when i just imitated some song or whatever, so do you have to be gifted to learn some decent singing or can you just train it although youre not that of a good singer?

you dont have to be talented, takes training.

In all honesty the way I learned how to sing was just by mimicking songs I listened to a lot, don't worry if you sound like an idiot when you first do it, it'll grow on you.
What I would suggest is just getting the notes down at least, if you can get the exact notes down you can form a technique around it, I've never had any vocal lessons in my life, I'm 100% self-taught.
I started out with singing Stairway to Heaven a lot, it's like the perfect song too. It starts out easily enough with really soft and low notes, and it warms you up by progressing in speed and higher notes. I use it as an exercise and then I try some Iron Maiden to get me a bit further.

But my main idea was to get it down PERFECTLY, then you can understand how your voice works and how the vocalist does it, so you gain a better understanding of vocals in general.
Also, you really need to learn vibrato. That gives you a lot of freedom in your voice, it helps you sound a lot better too.
Also, there is no need for breath control, you just need to prepare yourself for a long note if one may come up. If you know one is coming up just take a long breath and you can do it, nobody has like some alien sort of lung capacity or anything, it's all the same O_o

But I would suggest starting with an easy song, maybe some rock song (especially ones on the radio, all those vocalists suck dick) and just mimic it perfectly, then that alone allows you to do a lot more.
Just takes practice

okay thank you, i guess i can work (or at least start with that)

what do you mean by "taking down" notes? could you elaborate that for me?^^

plus, one of my closest mates is singer and she said that she always sung like she thought it was correct and had a lot of performances on stage and in school bands etc till some doctor told her she had knots on her membrans which may be there because of unproper singing techniques.

i think this wont happen with those few times a week ill sing but it wouldnt be wrong to learn it the right way, right from the start, would it?

i guess ill start off with stairway to heaven because im listening to it pretty frequently anyway.

yet i'd like to know how you listen to you own voice, because i cant really tell weather im doing it wrong or right when i hear myself singing?

should i record it?^^

Um well a lot of vocalists get warts in their throat if they overdo it, Robert Plant had to get about 10 throat operations from it.
And I meant to get the notes down, so just sing on the note and that's it, form your technique when you're comfortable.
And yea, record your voice and I'll record mine when I get it together, I could telll you what you're doing right/wrong.

Bullshit, Halford's last scream in Painkiller begs to differ.

wait... are you talking about singing or screaming?
either way, breath deep. but be careful, most people don't know what real deep breathing is. when you breath, your shoulders should really go up (you shouldn't get "taller"). when you breath try to expand your stomach. what you can do is place your hands on the bottom of your ribs and yawn really big. try to remember what that feels like and how much your ribs expanded, try to breath like that all time time.