Here are some special vinyl siding cleaner products you can buy at most home improvement box stores like Lowe's, Home Depot and Walmart.
Expert Chemical House Wash Home Depot $18
Simple Green House and Siding Cleaner
TSP or Trisodium Phosphate. Home Depot
Soft Bristled Brushes
Telescoping aluminum poles. Comes in several different lengths.This is a good tool to buy and keep around the house. You can attach many different attachments to it like paint rollers and window squeegees.