Best Directory structure for an installation?

I want most of my site to be powered by WordPress, but I would also like to be able to add some custom content that’s not affected by WordPress (custom php scripts, some html pages perhaps).

I’m using a static page as my start page and a subidrectory as my blog archive page.

So, I’d like to have something like this:
example.com – WordPress Start page
example.com/somedir/ – Another WordPress page
example.com/blog/ – Blog Archive page
example.com/customscripts/ – custom scripts and files that should not be affected by, nor affect my WordPress installation

Is there anything I need to keep in mind in this sort of set up? I can’t use customscript.example.com for my custom scripts, because I want to be able to post from example.com to some custom scripts (no cross domain posting allowed).

Tips, suggestions? I already have my site working like this. WordPress is installed at the root and I have a static start page. I also have a couple of directories with custom scripts in them. Dangerous? Better way to do it?