don't try any tricks,or shortcuts.
i'll give u a simple method to make ur changes more flexible.and if u follow it for 2 weeks,
u'll be strumming away...
now ur basic aim is to make ur chord changes smooth.
now getting to the base of ur problem ur not able to put ur fingers in correct position
when u try to change a chord.
like when u r playing a c chord and u have to switch over to f chord,
u start making the chord finger by finger,
here is when things go wrong.
so ur aim is to train ur mind to think of chords as a group and shape,and not make it finger by finger
start out by choosing any chord, i recommend A maj . put ur fingers in position press them down on the fretboard, play the chord.
now lift ur fingers slightly off the fretboard(so that ur fingers still touch the strings but do not produce any sound when strummed) without loosing the shape of A maj chord...
it should be like a batsman does with his bat he lifts it off and puts it back in the place several times.
now put ur fingers back down on the fretboard and play the chord again, do this several times till u get comfortable with the shape of the chord.
now lift ur fingers again while maintaining the shape of the chord,this time increase the distance to about one inch stop for about 4 sec and put ur fingers back on the fretboard,
repeat with this distance several times,
after that increase, the distance a little more.
similarily practice for other chords.
practice for about 15-20 min daily.
follow this ,and tell me how u progressed