With regards to the size, it varies depensing on the project. Regarding colour mode, select RGB. Regarding resolution, it must be 72ppi (dpi) as monitor screens display at this resolution. Anything else I can help?
Thanks for your answers guys, but there are some doubts regarding resolution 72ppi, what's the right in the case I need to print it ?
THe resolution of a file that goes to print needs to be at least 300dpi, but no more than 450dpi. Remember inreasing the resolution will result in a much bigger file size, so be careful with that.
For prints it should be in 300dpi in CMYK mode, do not use RGB. CYMK was made for prints and RGB was made for monitor use only.
You can use the standard web sizes as used in google adwords. For resolution, 72dpi is fine if you are working on web, RGB mode. For printing, you need to use 300dpi, CMYK mode.
Stander means what? size?resolution? or color combination? If you work for some one then his measurement is your stander.