Just trying to help... Post your own tips and I will try to keep them organized...
Color Selection
The 1st color MUST BE DARK! If iti s not then it will not update. Simply put, if you dont notice the colored circe (that you click to edit the color) changing color, then the color is too light.
TRUE COLORS
Use this trick to grab a team's TRUE colors... Find their true colors online, make an image of it, then upload it as a logo. Click to use the logo colors, and position your markers on the colors. If the marker changes to an X then the color is too light. After you do this, then click on any other tab, then go back to the LOGO tab. This will remove the logo color lock. Then upload the correct logo in its place over the true color image that you made and DONT click the box to use the logo colors again.
Image Editing
To edit images quickly and easily (still with enough muscle to really work with it) use this site...
http://www.pixlr.com/editor/
A quick way to to make sections of your logo transparent is to load an image into the editor, then unlock the lock icon in the LAYERS tab to the right, center and size the image, then use the WAND tool (hover over the tools if you dont know which it is) and select any section that you want to be transparent and press the DELETE button on your keyboard. Chose to save the image as a PNG file (dropdown box in the SAVE screen).