To many people this project could sound quite frightening.
Maybe you have an idea in your head already? Why not make it a reality then? Just tell yourself that you can do this! All you need to do, is remain calm.
I would recommend that before you make a start on this, that you put in some groundwork on your wall.
After all, you will need a clean surface to work on.
So, I would say give your wall a good wash down first, this is to make sure that you have no unwanted grime or grease on it.
Do let it dry thoroughly.
Personally, I would apply a primer first, like you would to a canvas, or simply apply just one coat of paint.
This can only be an asset.
As this most likely is to cover a large area, I would probably sketch this out on A3 paper by drawing 2 or 3 inch square boxes, what is called a grid actually.
Then work your design on the grid.
Once you have sussed this out, the next step I would take, is to work it so that you have exactly the same amount of squares on your wall area.
As an example, if you use 2 inch squares, one of these could represent 2 feet square on your wall.
You can mark your squares on the wall by using a coloured chalk that will show up on your painted wall.
Your chalk should be quite easy to erase afterwards.
Do not make the mistake of making your grid pretty small, or you may have difficulty getting rid of the chalk marks.
Whatever you choose to put in the grid, make sure that it has good, clear, outlines for you to follow.
Basically, using this method you need to copy your sketch onto the matching squares on your wall.
It is important too, before you paint, to consider which is the best type of paint to use.
In most cases a good make of acrylic paint should work well, but, depending on the size of your mural, this could work out to be quite expensive.
However, you could also use an ordinary type of paint you would use for the house, for the large part of your painting, the background etc.
The important parts could still be painted with acrylics, but do use a good brush.
One important fact to be taken into consideration, when you paint a mural, is that you are painting right on top of it all the time, so you need to take stock of it from a distance as you go along.
It may well be that the sun will reflect on your work, so you would need to choose a paint with this in mind.
Anyway, the paint needs a matt finish to it, so you will not suffer from the light bouncing off it.
I really think when you have completed your mural, it would be advisable to, as protection, add a coat of a clear varnish.
This will be a bonus later when you want to wash and clean your mural.