What is happening in Renaissance Music is you have the basic song. But what the author does is change the chord of as many notes as he can from what you would think the chord is supposed to be to something else. This is different from Bach. Bach many times makes it a point to change the actual key as often as possible and as soon as possible. That is why it is hard to sing along with Bach. But in the Renaissance, the author leaves the song intact, and changes only the chords. This idea started during the Middle Ages. The Middle Ages also had a few characteristic chords but that is a different topic.
Bach had a few ways to change the chord. Mainly to go to the dominant of the next key he is trying to get to. E.g. he is in C major and wants to go to D major. He will thus go  to A major and then to D.
[This does not work for half steps. But it does work for major or minor keys. I.e. in this way if he is in C major he can go to D Major or D minor.(But not D flat major or minor.)]

 He will also revolve around a certain note like they did in the Renaissance.
I have not really been able to use these ideas for myself, but I thought in case there are talented people out there that might find this useful I thought I should let them know.

[If I could I would share my own music with people, but I have not been very successful in finding a way to do that.]