When it comes to designing a logo there are things that you should know:

-A right planed logo usually don't use more than two or three colors

-Gradients and transparency's are more like a last choice to implement, but now with the digital printing is more accessible

-More than two typographies should not be used

-A cleaner and minimalistic logo is easier to remember and to read

-Remember to scale it down to 5x5cm to see if it works that small, usually it won't be smaller than that

-Start with B&W logo and when you got an almost definitive logo start working on the color, that way you will spend less time on the process

-Make a lot of sketches before you use the computer, that way you will have a more accurate idea of what you will be doing

-Remember the composition of things: balance, symmetry, etc...

-Monochrome designing is good, but don't rely on that, you can use applications like Adobe Kuler to find user made color themes

-Make the logo one color friendly

-Don't make more than 3 different logos for one client