From a viewers point of view the simplest design looks the best. Using a lot of different techniques can really mess things up. This is what I learnt in the long run.
Get to know the person before creating a design for them and then design according to their taste and personality. There are a few things to consider in this regard: Line, alignment, dull or vibrant colors, geometric or organic shape and typography. Choose a few templates to show them and see what they like while keeping in mind these factors. This has always helped me in being more creative while designing.