I suggest you first semi-close the blinds and then dust with a cotton sock.
Works like a charm.
You could also use a damp cloth.
If you really dislike manual work, a vacuum cleaner sometimes gets the job done.
lifehacks.stackexchange.com/users/82/QuyNguyen2013
Purchase a blinds duster.
Use it.
lifehacks.stackexchange.com/users/1508/Oenotria
The first thing to do is, of course, close them.
I wouldn't close them completely , as it may hold up the dust in the "folds"
(how can I call them?).
The next thing is to use a vacuum cleaner with the brush like this attached to the end of hose: image from vacuumcleanershop.com
lifehacks.stackexchange.com/users/21/nicael
I've found a vacuum to be the best tool for this job, as long as you have a brush attachment.
You still must run the brush along each slat
but it's much faster than a cloth.
There are even special attachments that go on a vacuum nozzle which clean several slats at once.
lifehacks.stackexchange.com/users/45/GdD
Take them down, leaving them fully extended.
Then put them in a bathtub full of hot, soapy water.
If they're really bad, include a gentle degreaser like Simple Green.
Let them soak for a bit, swishing them gently to loosen the dust and oils.
Then use the shower to rinse them off.
lifehacks.stackexchange.com/users/87/William the Pleaser
In my case I have such blinds on a balcony looking over a big boulevard so they get dirty quite fast.
The way I clean them is the following - I take down the blinds when fully extended and closed .
After that I take them to the bathroom and I use my shower.
My shower is with flexible hose like so that helps.
Now after you pour some water to the blinds they stick to either the floor or the walls.
In case the blinds are short enough I use the wall otherwise I use the floor.
Use strong flow of water and hit the blinds from one side to the other.
The dust literally flows out.
You may have to use some towel if the blinds are really dusty or muddy.
Cleaning the blinds using this approach is much easier but it is still a challenge for my apartment as I have about 20. NOTE: remember to remove the plastic part for turning the blinds otherwise it will constantly get in you way.
Now I also remove the small plastic part at the end of the strap for lifting the
blinds(after
I stepped on a few and broke them :)
lifehacks.stackexchange.com/users/2337/Ivaylo Strandjev
When I moved into my flat, I unhooked them from the window frame and gave them a shower.
lifehacks.stackexchange.com/users/2572/anonymous
I have  Venetian blinds  in my home.  I have a feather duster, but it does a  terrible  job, removing (at most) a third of the collected dust.  I've also used a standard dust cloth, which does a good job, but to wipe it across each blind takes much too much time.  What would be a more effective method?
How to dust Venetian blinds?
lifehacks.stackexchange.com
<home><cleaning>
lifehacks.stackexchange.com/questions/27
lifehacks.stackexchange.com/users/15/Mooseman
There are many different ways to approach cleaning Venetian blinds. One way is to close them and dust with a cloth or a sock or even use a special purpose blinds duster. Alternatively, you could use a vacuum cleaner or even remove the blinds completely and wash them in the bath. There are several methods for this, including wiping with a cotton sock, damp cloth or binds duster, cleaning with a vacuum cleaner or taking them down and washing them in the shower.
You could dust them with a cotton sock or a damp cloth or use a vacuum cleaner. Use a blinds duster. Close them, leaving the 'folds' partly open and then clean with a vacuum cleaner. Take them down and clean in the shower with soap and hot water.