Over the course of your growing cycle from cutting to harvest, you will almost certainly need to adjust your reflector heights. You need to balance getting your lamps as close as possible to your plants for maximum performance but far enough away that the delicate growing tips of your plant do not get damaged by excessive heat.
The cheapest way to hang your reflectors is to use simple chains and hooks, but a much more user friendly method of hanging your lights is to use an Ezi-Roll Light Hanger or a rope Ratchet Hanger (for heavier reflectors like air cooled reflectors). These devices make adjusting lamp heights much much easier and allow you to tweak your lamp set-up in minute detail for maximum effect.
Another device worth considering is a light mover - these rails allow you to cover a larger area per reflector, minimising power usage. Also, because your reflector is always moving, using a light rail allows you to get your reflectors closer to the tops of your plants as there is less heat build up (due to the constant movement).