For me, one of the main things I look for, when I'm using a new compressor, is how fast it's attack curves are. I generally want to avoid that I'm squashing the peaks too much, so it's about finding that sweet spot, where the transients just poke through, and then dip it. I do this by starting with the attack at almost limiting speed, and then slowly work my way backwards until the beats begin to have some air again.
Just be aware that you are always colouring stuff a bit. And if you compress more than around 3 dB then it will be very noticeable