Like any lens, unless you really have to touch it, don't. For regular maintenance you can use a camera lens blower/brush to clear of the dust build up. You can pick one of these up at a camera store. If you have a spot or finger print that must be wiped off, use lens tissues or laboratory Kimwipes. These will not leave lint nor will they streak. Avoid using liquids unless the spot will not come off with a dry lens cloth/tissue. If you must use liquid, use a lens cleaning liquid, not Windex or window cleaner. They contain ammonia and can damage plastic lens and lens coatings.
Hope that's a little help.
