Best way to solder my Arduino Mini Pro?

Good soldering is also about applying the proper amount of heat first to the connection before applying the proper amount of solder to the joint. It's really hard to teach soldering just by reading about it, but rather it's a matter of practice, practice, and more practice. Using some old discarded electronic PCB assemblies or other used electronics stuff is good practice material. It's an acquired skill and takes time to perfect. Did I mention practice helps a lot. :wink: