When selecting a template for the new website, the most important factor to consider is modularity, i.e. how module is the template's grid and how many slots it has available.
Note that you don't need to use all of those slots, but is it best to have an option. In practice, most website owners end up "un-checking" 80% of the existing slots and using very simple layouts. It is is much easier to un-check than to slice the template's HTML to add a new slot. So when selecting a template for your future website, select the most "cluttered" one, i.e. whose grid offers the largest number of slots.
Pay attention on how the slots are arranged, are they all of equal size, symmetrically situation one below the other? In some cases, you might want to opt for slots of different sizes - when you fill those slots with content (i.e. modules), your site will look more sophisticated.
I always recommend to my clients to select a template with a 3-column layout: one large column for the main body and two narrow columns on the sides. You can always NOT use one of the columns, if you are so in love with a 2-column design. But if you ever want to showcase a product or service offering, you will have an option of putting this information on the unused column and leaving it there alone, to make it more noticeable and draw attention to it.
Having a 3-column layout is also better for SEO, simply because the more words and links with your keywords you put on a page, the better it is for your ranking (as long as you have fewer than 100 links per page, roughly).
If you need help with selecting the right template, contact me via this blog or via our
website design Ottawa office at Joomla Bliss.