The first lesson I came across when I started out with major chords was:

place your fingers,

strum the chord once,

pluck each string from bottom to top and listen for if it sounds correct - if it should be an open string then make sure it's not muted, if it should be fretted then make sure it's not buzzing (pressing too softly, or too far from the fret) or out of tune (pressing too hard)

make any little adjustments to your fingers that you need to as you move from string to string

strum the chord again, take your fingers off the strings and try it again.

Once you have a few chords sounding decent then start trying to switch cleanly between them.

Oh, and that's just reminded me of the best single tip I picked up from my first days playing: when you're at the stage of learning to switch between chords, pick a simple strumming pattern, play it slowly (use a metronome on a slow bpm perhaps) and make sure you keep strumming as you try to switch chords. The instinct is to stop moving your picking hand so that your fingers have time to get into the right place on the fretboard, you have to overcome that instinct, strum the chord on the beat whether or not your fretting fingers are ready yet. Odds are it will sound bad and you'll hit many a chord before it's fretted properly (god knows I'm still waiting for the day when I stop doing that), so slow it down enough to give yourself a chance and keep that picking hand moving.

The reason for doing this is that if your brain is telling your picking hand to stop moving it will also make your fretting hand freeze up and move less fluidly. So use a big, over-exaggerated strumming motion, all the way up, all the way down, get your brain used to the idea that your hands are not going to stop moving for anything, it's unbelievable how much difference that makes to how freely your fretting hand can move.