Creating a new bedding area with shrubs.

I am new to gardening and have a large garden of which we have done little with over the last 12 years. I want to plant shrubs and perennials in a large bed which is approx. 4.5 metres by 1.5 metres and is at the front of my two storey house. Please give me tips on how to prepare bed/grass before planting. I hear mixed reports on using mypex, fine mulch? What is best?