How to write a shell script?

So any time I set up a Wordpress site for a client on my linode server (Ubuntu 12.04) I run these commands, one-by-one, via the command line. It doesn't take long, but its tedious.

I'd like to know how to create a script that I can execute from the command line that would encapsulate all these individual commands. It should:

1. Be able to accept a number of parameters (e.g. siteurl, dbname, etc…)

2. I need to be able to use those paramters as variables in the script (e.g. mkdir /srv/www/{siteurl}/public_html)

3. Where should such scripts be located? What permissions should I set on them? What are the naming conventions?

I imagine its fairly trivial to put something like this together, I just want to make sure I do it right and following whatever conventions there are for these kind of things.