abdominal muscles

All I can suggest is that you go to a large open space, where no-one is going to be bothered about a bit of noise and shout at the top of your voice. Just see where the noise is generated - it's in the abdomen, more specifically the diaphragm, but your stomach muscles are used to "pump" it.
That's where a good singing voice comes from.

hold your hands loosely 1-2 inches below your navel. (the chinese call this the "tan tien")
when you breath in deeply your diaphram and belly should expand outward,
this is the way to proper breathing and will help develop the strongest possible voice for singing.

edited

keep your back straight! that allows ur diaphram to take all the room it needs. One of the excersises we do in chorus is: Breathe in for 4 beats..hold for 8..and since u'd be new to it release for 12...then move up to 16...then keep going higher..it really helps..I can let the breath out for 36 counts. Also work on dropping your breath...filling all of your lungs instead of just the top which is what we usually do. umm..theres more...I just cant think of it right now..LoL

Try this link.

http://www.vocalist.org.uk/breathing_exercises.html

Fairly longtime guitarist, New singer here - one thing I was wondering about breathing excercises is how to apply the techniques when singing a song. Is it something that should simply start to become natural after you've practiced the excercises? How do you know when to take a breath when singing a song? Anyone?

in short , yes. the techniques will become second nature when you have practiced them like anything else. at first it seems unnatural but after a while you will do it without thinking about it.

the breathing techniques i was taught by my voice instuctors were exactly those taught by my chinese martial arts teachers

in life, babys breathe naturally without being taught the best way, later in life many of us learned the "wrong" way by filling up our lungs at the top and expanding out chest.
the only way to fix it unfortunatly is to "unlearn" the bad habits

the proper healthy way is to fill up your lungs from the bottom up, this insures that all stagnant air trapped in the lower sections will be evacuated and replaced with fresh air.

Also my sense of pitch isn't too terrible and I can ussually hit the note the first time but keeping the pitch is another thing, my voice tends to waver. Is this also to do with breathing?

air management is a hard thing most of the time i feel when i run out of air it is because i am streching my voice out of its comfort zone, which sounds funny and then the quicksand of strugglin to get back to MY voice..
a good practice to feel your voice is to project ones voice as if you were in a play and needing to reach the whole audience w/o amplification.. you will find this booming voice comes more natural ,and the predceeding breath is coming from the lower lungs cuz we know how to breath to speak, we do it everyday

keep your back straight! that allows ur diaphram to take all the room it needs. One of the excersises we do in chorus is: Breathe in for 4 beats..hold for 8..and since u'd be new to it release for 12...then move up to 16...then keep going higher..it really helps..I can let the breath out for 36 counts. Also work on dropping your breath...filling all of your lungs instead of just the top which is what we usually do. umm..theres more...I just cant think of it right now..LoL

What tempo do you do this to?

ie. bpm.

keep your back straight! that allows ur diaphram to take all the room it needs. One of the excersises we do in chorus is: Breathe in for 4 beats..hold for 8..and since u'd be new to it release for 12...then move up to 16...then keep going higher..it really helps..I can let the breath out for 36 counts. Also work on dropping your breath...filling all of your lungs instead of just the top which is what we usually do. umm..theres more...I just cant think of it right now..LoL

What tempo do you do this to?

ie. bpm.

Its in seconds.. Or atleast that is how we did it. Fill your diaphram up with air. When we say that think of it like this. When i normally breath in and out without thinking about it, my chest moves in and out. But what should be happening, esp when you are singing is that your chest really shouldnt move at all. I used to get mad at my teacher cause she would say DONT USE YOUR CHEST, and I could swear I wasnt.. But I was. The exercise that Cabre explained is great for expanding how much air you can manage while singing.

Fleaaa... the pitch will come with practice. I think probably your problem has alot to do with breathing.

Geoo

Well, since it's been explained, I guess I'll just suggest something. Try singing on the floor--that'll make you sing in the abdomen area.

What tempo do you do this to?

ie. bpm.

Its in seconds.. 60 then :mrgreen:

I'll be giving these excercises a go at the weekend, thanks everyone.