The earliest time to light the Menorah is shortly after sunset. However, if one lights before nightfall, one must be certain that there is sufficient fuel for the lights to burn for at least a half hour after nightfall. It is important to spend some of that time observing the lights.
Motsei Shabbat however, we specifically light after nightfall, and not before, in order to wait for Shabbat to end.
On Friday, the lights are lit before the Shabbat lights. This is critical. One may not light Chanukah lights once Shabbat has begun. Because of this, the candles should be large ones which will last for approximately 75 minutes (to cover the nightfall issue).
Right or left? The lights are placed from right to left, but are actually lit from left to right! Here is why:
This means that one lights from left to right. And the same for all subsequent nights.
RABBI MENDEL LEW