Q: I find it said in Maha Yoga that in the beginning of meditation one may attend to the breath, that is, its inspiration and expiration, and that after a certain amount of stillness of mind is attained, one can dive into the Heart seeking the source of the mind. I have been badly in want of some such practical hint. Can I follow this method? Is it correct?

Sri Ramana Maharshi :

The thing is to kill the mind somehow.
Those who have not the strength to follow the enquiry method are advised to adopt pranayama as a help to control the mind.

This pranayama is of two kinds, controlling and regulating the breath, or simply watching the breath.

Q: For controlling the breath, is not the ratio 1:4:2 for inhaling, retaining the breath and exhaling best?

Sri Ramana Maharshi :

All those proportions, sometimes regulated not by counting but by uttering mantras, are aids to controlling the mind.
That is all.

Watching the breath is also one form of pranayama.

Inhaling, retaining and exhaling is more violent and may be harmful in some cases, for example when there is no proper Guru to guide the seeker at every step and stage.

But merely watching the breath is easy and involves no risk.

~ From Be as you are book