Making Waterslide Decals

I bought some waterslide decals recently, and they were complete rubbish. Four of the sheets were really badly printed, the last time I saw colour printing so bad it was done on a 9 pin dot matrix. One sheet was a little better, so I tried to use it only to discover that the printing floated off the decal along with the backing paper and they look terrible on the car. These were from scalextric-car. co.uk just to be clear, I have previously bought transfers from PSR and they were great quality.

I decided that I may as well make my own, but couldn't seem to find much information here about it. Has anyone done it, and if so do you have any tips you can share? I have found some paper available locally and checked the instructions, I'm using an inkjet so will need to spray them with a clear topcoat. But I'm sure there are probably some do's and don'ts that I should know. Any tips gratefully received.