If its a cheap leather I use One Step gently agitated with a soft brush, on a cream/beige suite you can see the the soil coming off with ease.
Follow this up with a conditioner!
However I wouldnt advise this method, and certainly not on an expensive suite as some people on here say its not the right way to clean leather.
So use Chemspec Leather Cleaner & Conditioner, I have been told this is a good product.
Phil