Watch the Chord Flow 3: How to Practice online guitar lesson by Rich Maloof from Guitar 201: Breakthroughs
Changing chords smoothly is really all about practice, so that things can come more naturally. Thoughts on how to practice chord flow:
1) Keep time with drum loop or metronome. Play slowly at first, and only increase tempo after you can get through the changes without a mistake. If you miss, keep going. Think of it like a dress rehearsal: The show goes on even if your pants come down.
2) Don’t look. You can even play while you're watching TV. Just have the guitar around all the time, and load up your muscle memory.
3) Remember your cheats, like the zero chord, root notes, power chords, and muted strums.
4) Look for shape similarities between chords.
5) Consider different fingerings for your chords, and use the most comfortable ones.
6) You have to sell it. Practice assertively. Make loud mistakes.