Any new project should start with a plan.
Step one is to do some research. The easiest way of doing this is to buy a simple book on gardening. You need one with one of those charts that tell you when to plant things. There is a little point in putting something in if the growing season is wrong!
If you are feeling especially energetic, many regional areas have a local gardening club. These can be a valuable source of advice and inspiration, giving you information about things such as soil conditions.
Step two is to plan the garden. Most gardening books will talk about the need for detailed plans. Personally, I find a chair and a beer a great help here. The chair to sit on, the beer to drink while I study the back yard and sketch out an initial rough plan.
Now the point about the plan is not to make it too detailed. Remember, you are the lazy man (or person!). A rough guide will do just fine. And do have a beer after you have done all this work.