You can start with simple deep breathing but thinking and emotions are more important.Be there mentally and physically,and let Divinity enter you with Prana/breath.You can really call God with each breath,and with all involvement and emotions,as a child in need calls/cries for mother.You will start having different feelings in days.Never be scared of that feeling.When you remove dirt from within which is there since years,you are bound to have different feelings/impact on your body and mind.But feel yourself in the lap of mother,in the lap of God,and make a total surrender.More the surrender and devotion to the process,and to Divinity,faster will be results.Then gradually start reciting AUM,uttering it as long as you can with your breath and stamina,with the same emotions and devotion.Read my comments and quotes on this site,especially in 'breathing techniques',where I have given some simple exercises too.I do not recomend a teacher,because most of them take Pranayam as a physical exercise/process alone,which it is not.Make God your guide,sit before the photo of whatever God you believe in,if you feel like.That may increase your surrender and emotional level.None can guide,if God cannot.Be sure of that.I am there to help,but,I have no doubt,that soon you will be on the path to bliss,and will be exhorting others to follow this simple path to Divinity.I will let you know specific Pranayam Techniques as you proceed on the path.But those are matters of details,not of essence.Wish you all the best.

Udgeeth Pranayam—

"We do not believe in ourselves until someone reveals that deep inside us is valuable, worth listening to, worthy of our trust, sacred to our touch. Once we believe in ourselves we can risk curiosity, wonder, spontaneous delight or any experience that
reveals the human spirit."

e.e. cummings