Admins have special names, as you may know. For example...
Mentalistpro has a pink title. While this is not possible if you are not an admin for your main name, you can make your signature special and contain cool colors!
Like this; ~Jand(4th Wall)
If you want to know how to do this, I'll make another post later.
First, you'll want to create a new page called 'User:YOURUSERNAMEHERE/sig'. This will be a sandbox page where you can prototype your signature.
You can see mine here: User:Master Jand/sig.
Copy the SOURCE MODE text. Now make your own Sig page. Remember to go into SOURCE MODE. Paste it there. Then, replace all the 'Master_Jand's with your username. Replace all the '#B29670' with the color of your choosing. (Easy way to find the computer code for your color: HERE. Replace '4th Wall' with whatever you want to call your message wall. Most just call it 'Wall'. It should look like this when your finished:
Copy what you have in your Sig. Click on the arrow next to your profile image on the top of your screen. Click 'My Preferences'. Next, scroll down to 'Signature'. Replace the generic signature you have there with the pasted code. Scroll down to the bottom of the page and save your changes. Viola! Now, at the bottom of comments and posts, remember to enter down a few times, then type 3 tildas, or these things: ~
Thanks for listening!
If you're looking for something more advanced, you can try adding symbols and such to your main name. For the cool look I have on my signature currently (gradient of green) you can copy and paste the code I have here: User:Master Jand/sig2 and replace the 3 color codes (#COLORHERE, #COLORHERE, #COLORHERE) with the gradienting colors of your choosing. You can even add pictures from the wiki, onto your signature. (An example of this is Mental's Signature)
Actually, I wouldn't recommend using signatures in comments, since comments are usually pretty small, and signatures may be a bit of a distraction, but I'm not saying you can't. Using them in forum and message wall posts (like I do) is completely optional; the only thing where using them is mandatory is talk page additions.
Also, colour customization for the links themselves is done at MediaWiki:Wikia.css, but that can only be edited by admins. You can have your own personal CSS code page, whose changes and additions are only visible to their user.