All the blind should be cleaned while they are hanging up. Make sure that you are going from top to bottom, and get into a weekly schedule of vacuuming and dusting every week. Vacuum this way, then follow through with a duster that is made from a natural material to pull the most dust off. Don't start at the bottom since you run the risk of knocking them loose or breaking them.
To clean them, wipe them down with a sponge and soapy water the same direction that you dust. Follow this with clear water on the sponge to remove any soapy residue. If you have a tough spot for a stain, spray an all purpose cleaner on the sponge and spot treat the area. Do not spray any cleaner on the window blinds directly, as it can cause damage and discoloration.
If you feel that your blinds are very dirty and you can not get them clean, then take them to a professional cleaner. You may also find that you cannot properly reach the entire blind or that the task is too time consuming and a professional cleaners can help you as well. You can find them online or in the phone book and they will generally be listed under drapery cleaners.
For those that have fabric blinds, you need to make some extra precautions so you do not ruin them. Do not soak the window blinds in water, or use hot water anywhere on them at all. To do so will cause damage to the stiffening agent, as well as cause shrinkage and loss of properties such as flame retardation.
Never dry fabric blinds in a dryer or wring the excess water out since both of these can damage the window blinds beyond use. They will retain more water because of the cloth, and you need to gently blot the excess water from them, and dry them by hanging them back at the window.
While you clean them, make sure to look at all the small parts that make the window blinds up. If you notice any damage or anything that needs to be repaired, do so as soon as you can to make sure that they will become a hole. The places to get replacement parts can be found online, and you can find plans that show blinds to make sure you are ordering the right part at the site as well.
You do need to perform some upkeep on your vertical blinds, and cleaning and keeping them in good repair can make sure that you enjoy them for many years. This can help you keep from having to replace them, which can save you money. Make sure you are attending to the cleaning at least once a week and they can hang for many years.