Hi Aleks!
I, too, am new to e-forming - and have many questions as well. Just to let you know, we are also discussing this same topic in this thread that preceded your posting. Here is the link so you can see what we said there too!
http://lampworketc.com/forums/showthread.php?t=239946
Although I've only e-formed a couple items so far, I have found that if I take a brass brush to my piece as soon as it's rinsed and dried from the e-forming solution, it brightens up to the "new penny" copper color in a snap! Have you tried the brass brush technique yet?