The best place to start is probably
Mixed in Key - a very good tool for helping you to identify harmonic compatibility. It's not free, though, and also has Always-On-DRM, which I personally don't support, so I don't use it. I use
KeyFinder, which is a Free/OpenSource alternative that is not as accurate, but is still quite accurate - it works for me mixing Funk, which has a lot of the same problems you will face doing RnB.
What it comes down to is - if two songs are in the same key, they are much more likely to mix well together. Pretty straightforward. From there, you have the Camelot Wheel (in that first link, it talks about that) which shows you how you can move from key to key. For example, D minor is a very common key in Funk (and probably also in RnB)... in the Camelot Wheel notation, that's a 7A. Looking at the wheel, it is generally safe to move from there to 6A (G minor), stay in 7A, or 8A (A minor) or transition to its relative major key, 7B (F major).
When I say that the chord progressions are also an important consideration, this is because chord progressions can change the harmonic feel of a song for each chord change - just because you're working in F minor doesn't mean you are always playing an F minor chord... otherwise known as the "I" (one) chord. If your song is playing the "IV" chord for the second quarter of your phrase, then that would make it tend to clash with another song that might be in the same key, but is playing, say, a "III" or "V" chord.
That said, start by identifying the keys of your songs... then, you can trust your ear and experiment. Find the tracks that mix well together. You don't need to identify every chord being played, that would be far too much work, but if they are at least harmonically compatible in general, you'll know you're in the right general area and from there, your ear will help you with the rest.
Bookmarks