Answer: This is such a large scale, long term project that it is worth doing a lot of planning ahead of time. It is easier to make changes on paper than it is on the ground with a shovel!
I would suggest you begin by making a wish list of the uses/activities/want items you would like to use your yard as a starting point. Then you should identify the trees and shrubs and any other existing features that are worth saving or can be adapted to suit your needs.
You might want to consult on site on an hourly basis with a designer or landscape architect to help guide your initial overall planning.
A scale drawing or sketch (you can do this yourself) can be helpful at this stage in terms of estimating sizes, quanitites and costs. Then work out an overall landscape plan that you will implement in stages. If you break it down into steps it is less overwhelming.
You may find that your local county extension and also local nursery personnel can be helpful in identifying plants that would meet your criteria and grow well in your yard with minimal work. Some nurseries will also offer design help at minimal cost if you purchase your plants from them.
In the meantime I would suggest looking at magazines and books for ideas. One series I really like is the Dummies -- Landscaping for Dummies and Gardening for Dummies are great for starting to think about how to make the changes you want. They are full of practical how-to tips and straightforward advice.
Good luck with your project -- it is always rewarding to see how a landscape comes around!
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