...I found on google image search...I need it for print...
Isn't this more of a legal copyright question than a Photoshop question?
it's for personal use, so I don't think it should be illegal.
The mention of '300dpi' indicated a likely intent to use a professional offset printer using a traditional line screen.
If this is for personal use then you'd likely be using an inkjet printer. That is a different printing process that does not require 300ppi. You don't need that much resolution for inkjet.
I would like it to be in a higher quality since I'm sending it to a photo store, so I could print it in the best possible quality. I don't think that the fact I want the best quality means I'm going to use it in a professional way.
And to my original qustion, what is the best way to impove the photo (if it's possible)?
there are better images available:
(1) search strategy
(2) a result
Upsampling is quite useless - one needs enough original pixels.
Image (2) can be improved by Level Adjustment and by Sharpening.
Best regards --Gernot Hoffmann
Message was edited by: Gernot Hoffmann