I was working for a safari company based in the Okavango Delta. Myself and one of the guides were scouting out the area one morning in Savuti, Chobe National Park. All of a sudden, we came across this leopard, lying in the grass, monitoring the area for prey. She was known to the guide and was a new mother, who was denning in a nearby rocky outcrop. We only stayed with her for a minute, but at only around 3 metres away, I will never forget her looking straight up at us!
This is one of my most intimate wildlife shots, as it is not often that you can get this close to a wild animal (sensibly and respectfully).
Into the Eyes
I recommend a border of at least 1cm just so you don't lose any of the picture in the mounting or framing process. I personally like to use a larger border (around 3cm) on the larger prints, especially if you don't intend on mounting them, this is more for aesthetic reasons.
A 12x16" print with a mount would require a 16x20" frame