"Attacking" the sound is a very strong word for two tiny vocal chords which
simply need to connect and vibrate without being "attacked" by too much air or a
glottal push. The secret to a good sound right at the start is the opening of the throat.
If your throat is very relaxed and open wide (not the mouth but the inside of
your throat) then the "attack" comes naturally.
Beginners usually start the sound in two ways:
1) Breathy sound - that means the chords have not enough contact with each
other and the airflow comes in between them in a way that weakens them
However it is a soft approach and does not hurt the vocal mechanism.
2) Pushing against closed vocal chords. Glottal attack. That's when the throat
is not open to begin with and the chords are closed. If you push through
with a forceful attack then you get a small "popping sound" which is not
healthy, especially if you do it over a longer period of time.
How to do it well. An exercise for opening the throat:
Take your thumb and forefinger and let them touch at the fingertips.
This represents your throat in a closed position. Now hold your fingers up
to your throat and start slowly and gradually to open the fingertips away from each other.
As you do that try to think of your throat and visualize it opening as well.
Don't breathe in. Hold the breath yet open the chords.
When the throat opens you will feel it in your belly. Your belly will
expand and your ribcage as well. The more often you do this the wider your
throat will open. Be patient and be focused when you visualize.
You can help yourself with images. If you imagine being very surprised and
opening your mouth wide (while you hold your breath) it can help you.
But just the fact that you are trying to feel and visualize the chords is
going to help you get in touch with the feeling of opening the throat.
Once again: you can tell if it works by the belly expansion. If nothing happens
in your belly then chances are your throat did not really open yet.
Once you feel the belly and the throat opening then you can start the sound.
Imagine that you have created a big barrel. Your belly is open, your throat
is wide and then set the sound in the center of this barrel and start the sound
as if you would drink it, pulling it into your body very gently.
Patience is key. You need to rest in between but stay at it for at least 10m.