Two women doesn't make you twice the man, it makes you HALF the man. You best be twice as good as a normal guy to even begin to be worthy because, let's face it, a normal guy for most women is not terribly impressive.
It helps if you have one chick already interested, then you can enlist her into the seduction... if your partner in seduction is genuinely interested in getting a little lesbo action herself, it goes a long way both to getting and helping ramp up the heat in the moment.
This isn't even touching on purely pragmatic and practical matters (such as increased possibilities of positions, dealing with jealousy where one or both feel you're paying too much attention to the other, etc). As you probably already know, porn isn't reality and that's true for threesomes (or more) as well.
On the plus side, when things go good, they go realllly good. There's nothing quite like the ego boost like knowing you've done a good job... except maybe knowing that you've done TWO good jobs!
Makes for some great tales around the campfire, too.
