Holiday handcuffs.

The quickest way to bind your partners hands is by using the so-called 'Holiday handcuff'. 
It has several advantages, amongst them, that it requires about 3 feet of rope, and about 10 seconds…
On the other hand, there's only one rope around the wrists, which will result in a considerable strain, if you use it for i.e. suspensions ( we'll get back to that ).
But in order to hold your partners hands, while you're preparing one of the bigger bondages, or for D/S-play, it's rather good.

1/ - 4/  The preparations in the first 4 stages is the same as the clove hitch, which you'll find HERE

5/ Here you pull the two loops 'through' one-another. 
In other words, you pull the green loop up through the blue loop, and the blue loop down through the green loop.
Take care that the ends do not slip through though...

6/ Now you pull the resulting loops big enough for your partners hands, and slide them through either loop.

Finally you tie a reefers knot on the ends of the rope, to lock the bondage, and now you've got a handcuffed partner.

Now this version is not alltogether the ideal one, so here you'll get another version, which is somewhat better.
However it's got the same limitations, as the former one; so do not use this one for suspensions either !

I've left the 'knot' open, to let you see what's going on, but the twine needs to be quite tight, though not really tight, as this will come when you tighten the handcuffs.
Again I've let the one end of the rope be green, and the other end blue, to let you see what goes where.

1/ Lay 5-6 twines around your fingers, not too tight.
    Pull them off your fingers.

2/ Make a loop at either end of the rope, and pull them through the twine, from either end.

3/ Now pull the loops to tighten the twine, and do mind the ends... 
Slide your partners wrists through either loop, and pull the ends to tighten the loops around your partners wrists.
Lock the bondage by tying a reefers knot on the ends of the rope.

Here you got them both, as they look in the real world.