Listen to a lot of the hits....
There are certain characteristics that recur on a lot of the songs - the classic bass line/bouncy drum beat on 'You Can't Hurry Love', guitars usually just playing on the off-beat (with snare hits), tambourine on the back beat too, and that really thick, prominent, melodic and often over-driven bass sound. That bass pretty much informed Paul Mccartneys bass style..
Vocals often recorded very 'hot' so that they distort slightly when they reached for those amazing high notes...also makes it sound like there is a lot of energy in the song. (Reach out is a great example of the 'hot' vocal)
Vocal style and melodies originated in Gospel singing, so call and response techniques used a lot (Please Mr Postman, lots of the Four Tops stuff).
Exuberant vocals/riffing was avoided. You dont hear any mariah carey/christina aguilera/whitney houston style theatrics..
In the same way, arrangements were simple. Often just a piano/guitar through the verse and perhaps some pop brass/strings in the chorus. Songs were driven by the bass and all hooks reliant on vocals...
Most of the songs dealt with love aswell...
Thats classic Motown. Otis Redding, to an extent (Dock of the bay), and then Marvin Gaye with 'Whats Going On' opened up a more artistic path...
Of course, it all hinges on having an amazing soulful singer...