Truth is, I am going to tell you how to design C.R.A.P. instead of crap. I learned this while in design school at Humber College and it goes like this;
Colour: I learned colour instead of contrast because there are a few “laws” when it comes to colours such as contrasting colours versus complimentary colours. You also have the psychology of colours, i.e. red means stop, green means go, orange means cheap, blue means trust-worthy, etc.
Repetition: nothing brings a sales point home like repetition, although in the context of design this really refers to consistency is your colours, your fonts, your shapes, sizes, etc.
Alignment: I recommend you all text with the same alignment (all left, all centre or all right). The human eye is conditioned to read in blocks of text or paragraphs. A successful ad/poster is quick and easy to read.
Proximity: negative space (empty space) is another term that can be used to describe “proximity”… be sure not to cram too much on the page and clutter things up, you want to have a safe distance between all elements in your design. Contrasting colours may help you cheat proximity in your design.