Here are a couple of ideas from a relative WordPress newbie.
Open up your blog page in a browser and then use the view source menu option. You can then find the class name for the text you want to style. For example, I opened up a browser for a test blog on my PC and found the following HTML in the source code:
<a href="http://buddy/wordpress/?p=40#more-40" class="more-link">Read the rest of this entry »</a>
The code shows a couple of important things: it shows the styling class name for the text, "Read the rest of this entry »". The styling class name is "more-link".
Here is how I styled the "Read the rest of this entry »" message:
I Opened the style.css file for my theme with a basic text editor. The CSS file was in the \wordpress\wp-content\themes\yourtheme directory. The class name of ".more-link" did not exist in my style.css file--so I added it to the end of my CSS file:
.more-link { /*don't forget the period in front of the class name*/
color:red; /*change the message color to red*/
}
This changes the color of the message to red. If you wanted to stylize the link behavior, you could add the Anchor Pseudo-classes to the style.css file, referencing the .more-link class, like this:
a.more-link:link {color: #FF0000} /* unvisited link */
a.more-link:visited {color: #00FF00} /* visited link */
a.more-link:active {color: #0000FF} /* selected link */
a.more-link:hover {color: #FF00FF} /* mouse over link */
As for the text, I opened the index.php file for my theme. I found this:
<?php the_content('Read the rest of this entry »'); ?>
I changed it to this:
<?php the_content('More »'); ?>
For other navigation links, the problem appears to be more difficult. What is really needed is a class name added to the generated link. You might look at
http://trac.wordpress.org/ticket/6109 for an idea of what might be involved. Perhaps someone a lot more familiar with patches and PHP can add some advice here. This is a very interesting problem.