1. I have just installed WinSign and a MK3 X-card, but I don't get a good printing result. What shell I do?
The MK3-system requires that you put the printer as a default printer before you start WinSign. Check this and contact Partex if it doesn’t solve the problem.    

2. Why are the orange and red indicators flashing on my P310 printer? What should I do when I can read the message CLEAN PRINTER in the display on my P330 printer?
You must clean the printer.

3. What type of black ribbon should I use?
Always use the 301E ribbon from Zebra (Eltron)