Sitecore templates are much more flexible compared to Umbraco document types/compositions, so keep that in mind. There is no muli-level inheritance in Umbraco, so you can’t for instance do something like this that you could do in Sitecore:
- Website A homepage
- Website A base
- Generic website base
- SEO composition
- Base composition
- Generic website base
- Website A base
I wrote a discussion about this, comparing it to Sitecore:
So you can have some base compositions, but you need to apply them to every page for every site seperately, like this:
- Website A homepage
- SEO composition
- Base composition
- Website B homepage
- SEO composition
- Base composition
- Website C news overview
- SEO composition
- Base composition
By default all template files (Umbraco templates, not Sitecore templates, so the visualisations) will be placed direcly in the views folder, so it’s best to give them a good alias. Also read this topic for inspiration:
When it comes to code, it’s just a matter of preference. I always try to write as many generic components as possible (View Components for example) so that the pages themselves don’t have that much code (and possible duplicate code). If the sites are very similar, you might use the same code for everything and manage the differences via the Umbraco backoffice. We have some sites that are so similar that you can just enter the URL to the stylesheet and the favicon in the backoffice per site, the rest of the code is the same.
Hope this gives you an idea where to start.