There are many visualizations which can assist with distance healing. The easiest approach is to decide which way to send the energy to the person. Will you send it to them via a cord of energy? Will your energy-self bilocate to the target and heal them directly? Or will you pull some of their energy to you and heal it, sending it back afterwards? The last option is the most difficult, and least efficient, so let us concentrate on the first two.
Sending Your Energy to the Target Through a Connection
This method is straightforward - you must visualize a "cord" or "umbilicus" (or whatever imagery is most potent for you) that travels to the person and connects with them. This cord must have a channel for sending energy through to the target, and a channel returning for "feedback" on your healing progress. If you find that your energy dissipates before reaching the target, try shielding the cord with a reflective surface on the inner surface to keep energy from escaping. This intent should up your power potential.
Then, intent the energy to travel through the cord to the target, and instructing it to either heal the location at which it is located, to travel through the body to the afflicted area, or to cause a "blanket effect" over the person, healing anything it can. When the healing is finished, dissipate the connection slowly, without "breaking" it off quickly; this can cause some psychic backlash or else a nasty headache.
Energy Bilocation to Healing Target
This technique is slightly more complicated. You must "lock on" to the target's location, and imagine your energy self there. It requires more focus and concentration to hold that image and the healing intents, but it can make up for energy path-loss with distance connections.
When you have arrived at the target's location, you may begin healing by "touching" the person and transferring energy, or whatever method is more comfortable for you to accomplish. When you have finished, merely re-transfer your conscious thoughts back to your body and your energy self will retract. Attempt both methods to find your comfort zone, and then try to bolster your weaker method. One can never know which will be needed under specific circumstances.