User Level: 
Click on an image to make it bigger.
Pathauto - URL Path Pattern Configuration - Settings - General

1. General Settings

Go to Admin Menu > Configuration > Search and Metadata > URL Aliases > Settings tab.

At the top of this screen exists many different general settings that control elements of your path.

The default settings are fine for most sites.

Verbose checkbox

Separator field

Character Case options

Maximum Alias Length field

Maximum Component Length field

Update Action options

Transliterate Prior to Creating Alias checkbox

Reduce Strings to Letters and Numbers checkbox

Strings to Remove field

Pathauto - URL Path Pattern Configuration - Settings - Punctuation Handling

2. Punctuation Handling

Click on the Punctuation fieldset to open it.

Punctuation can be a real problem for URLs. At a minimum it can cause confusion for your audience. At its worst, it can result in a broken link.

Spaces can also wreak havoc in a URL as well. At a minimum the space will be automatically filled with a %20 code, which can be really unsightly, especially if there are many spaces in a URL. At its worst, if the space isn't encoded, it can also result in a broken link.

Pathauto provides ways to configure how every different character is handled. The default settings will typically work just fine.