It’s a common mistake many designers make: come up with an awesome design, then try to fit the content into whatever space is left. Too many designers start working on a project before they have the content (copy, images, etc.). The problem with this is that our job is to take content and make it look good, not to make something that looks good and try to squeeze in the content, this defeats the purpose of our job.
You will save yourself a ton of time and headaches if you are sure to get content before you start to design or layout anything.
This is true for everything from posters, to brochures, to a website or a simple business card. Trust me on this one, it will make all the difference in your final output and the time spent designing. Know what you’re working with first and the rest will fall into place.