If you have a template file, import the styles from there if you want (so you can import them back later on!).
Anyhow, do NOT make these definitions in your text or template files. Here is why: Many elements will use the same paragraph tag, but they all look different. So when you change a definition in the Template or text file you will never really know what the base configuration of your paragraphs was. You will have to painfully reset the paragraph definition to what you forgot it was. The good News is that when you import paragraphs from your styles files and ensuite the EDD definitions you can override all local definitions in your Template file or elsewhere (means that recovery is easy if you stick to my plan).
Make them look nice. For all of these, do not think in terms of standard FrameMaker or Word paragraph definitions. Think of something from which element formatting rules will inherit! That basically means use standard indentations, use the smallest font your smallest title will use and so on ... If you don't understand this idea, read the next steps and come back.
Warning: Do not rely on default Paragraph Names if you work in a multi-language organization. Maybe the default paragraph for Titles is "Titre" or whatever. This is another reason why you should start by defining at least one "base paragraph". (Later on, to be safe you have to tell EACH element in your DTD to rely on one of YOUR paragraph definitions. I did not do this in my little Stepbystep EDD (but should so).