Notes in melody to change chord progression?

I dont know how I put it, but is there any methods when playing melody to decide notes to "prepare" ear to change in chord progression or triads.

forexample if playing C major say IV III I V chord progression and change it to E minor chord progression. If you know what I mean.

It might be that Ive noticed something like this in some lessons, but amount of information been so huge lately, that I dont recall everything. So it is very helpful if you can point lessons if there any to help in this case.

Thanks in advance
Empirism

Well, to go from C major to E minor, we need to change that F to an F#, right?

Well... lead into it that way. :) The best way to do it is to lean your way into a new home position. Since your home position right now is that F chord... we need to make it an E minor. Well, the best way to do that is to lean into it from the G major chord... which you are ending your progression on.

That should sort of just flow through on its own without too much problems with the ear. If you play the notes pentatonically... they are the same... so you can probably get away with a lot doing that kind of a key change.

I don't know if this helped at all... :/ sorry! My brain is fried from tests

One way to go about doing that would be find where the notes crossover; kinda like what JustJeff said. Or you could break the progression down into seperate chords and keys. For example:

C major : C D E F G A B

G major : G A B C D E F# 

Next, pick a scale from each key. Say A Aeolian and E Aeolian. Find where the notes cross over. You will notice that both scales contain the notes C D E G A and B.

So lets say you are chugging on the C major chords. Perhaps play a short one or two bar lick focusing on the note F. Then slide up to F# and start chugging on the E minor chord.

Sorry if that wasn't very clear, I haven't touched my guitar in over a month. Hope it helped though.