For me, the healing energy comes out of my left hand, while my right hand does the absorbing or taking out role... after which I offer my right hand to the light for whatever stuff it collected to be burned/cleared/transformed.
This worked naturally for me from the age of 17. But over the years I started to direct the energy coming through my crown chakra down into my left hand, and I would breathe out as it went into the affected area, which was quite draining in a way.
Two years ago while working on a man with very aggressive throat cancer, the process changed. I got told to allow the energy to do what is needed and so I no longer needed to direct it.
This meant simply keeping my mind out of the equation altogether, which took a few minutes to get the hang of! After that, the energy coming in was massive, it poured into the crown chakra and straight into my left hand to do it's work.
You will know when the healing energy is coming through you, it ranges from a beautiful warm feeling to quite hot, depending on what is being worked on. More importantly, you will feel this heat moving into the person you are working on, and, they will feel it too.
You can also direct the energy to any place you wish. As an example, I've often directed it into my finger tips so that the fingers feel like they grow 6 inches longer in order to do 'psychic surgery'... for want of a better term. This has been very useful in cleaning and powering up other people's chakras that may seem stalled, etc, and for directly removing large portions of "dross"... that ugly looking dark-gray to black stuff you see inside the area being worked on.
Personally, I think the most effective approach to take is to be prepared to work with others, and then offer help when asked or needed.
You will know when you need to act, because the pressure to do it will become intense until you do something about it. This can and will happen at times you might not want it to, such as at a party for instance. This is for a reason, so you get over your inner worry about doing the work, and to balance the ego so that you can do what you need to do no matter who else is around, etc.
You could practice on pets, friends, etc.
Most important: Have faith that what you do works!! Don't doubt it or you may weaken the effects. And, never think or say, "I healed that person", because Ego will run unbalanced afterwards.
I hope this is some help to you.