While shifting, simply imagine you have a boiling hot cup of coffee with no lid between your legs and a really rotten egg between your shoe and the accelerator pedal (don't smash down on it and break it, or let up so fast it falls out from under your shoe and breaks in the floor). 

If you get 'rammy' with the accelerator while shifting, you'll suffer the consequences (imaginary scalding coffee & broken rotten egg).  Acceleration under power happens when its fully in gear, not while you are between gears.  Best to practice easy on and easy off when shifting, get the engine rpms to match the gears and let the tranny slip/fall into gear.