Start like you did when you learnt to juggle with your eyes open i.e. toss one ball from hand to hand, then two, then three.
Your throws will have to be considerably lower than normal to make catching without vision feasible.
Timing is vital; with such low throws the balls are very nearly hitting each other. Try to visualise the balls positions.
Another option is to juggle with eyes open, make the pattern very small and low, then close eyes for short periods whilst still juggling.
Initially there is very little scope for adjustment, best to focus on making the throws so accurate and low that they land in the other hand. Later on you'll gain the ability to 'see' in your minds eye the location of the balls. Also, with a fudged catch/throw, by feeling where on your hand the ball leaves from, you'll be able to predict its path and reach out for it, possibly saving the pattern from collapsing.
Balls- the crocheted ones are excellent (see: -
http://www.homeofpoi.com/ubbthreads/showflat.php?Cat=&Board=UBB1&Number=157427&Main=157427#Post157427
for how to make these) cos of the noise and tactile properties. Failing that, any standard beanbags will work, it's better if they're old and floppy as they'll be less likely to bounce out of your hands. Stage balls are, for me, a no-no; difficult to catch and they'll roll for miles when they drop.
Position- Kneeling down 'seiza' style is good, bear in mind that you'll be dropping a lot and if you're kneeling you'll generally be able to locate the dropped ball without having to take off the blindfold. Generally, with most juggling stuff it's important to be standing, but, for blindfold juggling, you'll be better off close to the ground till you've got the basics.
Tricks- 'Over the top', 'half shower', 'reverse cascade' are all feasible, as is transitioning between them.
'under the arm' is trickier but achievable.
Years ago when I practised this regularly I could get a few passes of 'mills mess', not consistent, but, with practice, it could have been.
Why?- blindfold juggling is a unique experience; whilst it has potential for use in an act I feel that it's main benefits are purely personal ones.
It's hard to describe what it feels like to be juggling with no vision, it's very peaceful and relaxing.
With no visual feedback your allies are imagination and the ability to throw low, accurately and with perfect timing; to a lesser extent the noise from the balls helps.
On occasion, when the pattern is steady and balanced, you get such a good impression of the position and state of the balls that there is an almost visual representation of them in the blackness of your minds eye.
How difficult- I can't really answer this; I picked it up fairly quickly but I learnt it at a time when I was doing lots of very intricate three ball work (with eyes open!), much of which involved very quick flurries of low throws. So I guess I had an advantage when it came to closed eye juggling cos I was used to maintaining tight and low patterns.
It'd be interesting to hear from others who've worked on blindfold juggling, or progress reports from any one who decides to give it a go.
Good luck.
Your minds eye gets a little hint, but that's all. 
Previous Topic
Index