Right off the bat I would say you don't need to feed your plants as much so go light on the nutes. You'll be watering less too, so be careful of overwatering otherwise you'll trash your roots. Don't treat your LED as a drop in replacement for your HID. Depending on the light, it might take a grow or two to see what is the best way to hang it.
Other growers around this section have switched from HID to LED so hopefully they'll chime in with some more practical advice for you, but the above advice is a good start. Good Luck and Happy Growing!