Building a Pedal continued...

[Flavaham]

I'm done with the circuit board on my pedal.  This is the first pedal I've built or done any mods on.  It is the "Tweak-O" from Small Bear Electronics.  The schematic and other info for it can be found here:  http://www.smallbearelec.com/Projects/TweakO/TweakO.htm

I'm wondering how you go about deciding what parts to replace to improve the sound.  There is a list of all parts at the bottom of the page.  If anyone can suggest some upgrades, please let me know. 
Thanks!!
-Gabe