I use Putty a lot and it always opens in quite a small window. I wondered if there were any parameters or settings I could change that could make it open in a window of different size by default.
When you open PuTTY select Window in the tree on the left:
You can change the number of rows and columns in the Window here.
Alternatively, select Appearance and change the font size:
Once you're happy with your settings, select Session and then save these settings back as "Default Settings":
These settings will now be the default for new PuTTY windows.