I don't think so, as far as a gun, I'm not sure what you could do to non-magically prep the bullet/shot. It's going to come out any faster or hit any harder. 

As far as melee goes, usually most people don't count it as a prep since it has no magical properties. While, yes, doing those things could make it stronger, we just don't look as it as a prep unless there is some type of magical properties to it. At least, I don't. 

And depending on your interpretations of the rules(I may be wrong on this, Skalla is the poobar of it), some places I don't think you can charge AND use the attack in the same post. Like Adinraen(R.I.P, homie), didn't charge up the earth pillars on the same turn he summoned them.