When you are in the process of healing someone, begin by concetrating on not how the person feels, but how you feel while in contact with that person. The disruptive energy contained within your client will attempt to spread itself to you - and while this is not a good thing on the surface, it can be used to your advantage. You should be shielded before healing to prevent this effect, however, you will still feel 'sympathetic' effects from the disruptive energy and your connection to your client.
Notice any sudden twinges of pain, or shifts in consciousness. These can be strong indicators of problems that are existing in your client. Use your own feelings to guide your energy to the most efficient healing locations. Relief of your own symptoms is usually a positive sign of properly applied healing. When you have managed to alleviate your own symptoms, you may begin to 'wrap up' your energy transfers and intents, and leave a few behind with the intent to continue healing or act as a 'watchdog' to prevent from relapse. Continued practice with this technique will greatly refine your ability to treat acute symptoms with greater speed. If at first you do not feel anything, do not be discouraged. Open your mind to subtle feelings and even some 'gut' feelings. Your client will thank you in the end.