Practice Em to Asus2 (Am without B string) then

E to Am ( same shape up and down)

E to Asus2 (up and down lift a finger)

Em to Am (up and down lift a finger)

switch between arpeggiating and strumming

also finger a chord and lift pluck holding down other strings to the notes fretted up and down (gets you used to lifiting)

Try to make it all sound musical and when you mess up keep going. Don't teach yourself to give up.