It really depends on the key of the track. Take a look at this
chart for reference.
With my sub kick, I tend to apply a smooth cut between 75 and 100, again, depending on the key of the track. Some people prefer a harsh cut because it can add a bit of resonance to the kick, but that's not really my style.
With the "clicky" kick, at the very least I'll cut everything below 900Hz, sometimes a bit more. Then, when sending the two kicks to a bus, I'l turn the "click" kick all the way down and slowly raise it. I want to be able to just barely hear it as it comes through the mix. The reason is that if you turn up the "click" kick too much, when you go to throw a compressor/saturator/etc. on the kick bus, it's going to really muck things up. I'm a big fan of subtlety, though there is a time and place to be aggressive, but I digress.
Finally, one thing I always do is after I've got a very rough drum kit made, I'll bounce it down and listen to it in my car so I can hear how all the sounds are coming together...and most importantly, how that kick is feeling.
Perhaps the best tip I can offer is that the best sound comes down to having quality samples to begin with. As it's been repeated many times on the forum:
you can't polish a turn. If you're not feeling that kick (either layered or separated), find another sample–it will save you time and a bit of sanity.
I've had less than good luck with some Vengeance packs–that's not to say there isn't some gold in there–but it requires a bit of digging.
I'd recommend the following packs for good kicks (and snares) with loads of headroom: Prime Loops Future DnB Drums, Loopmasters Loxy & Resound Artist Series and K-Tee Shogun DnB. The BHK Rough Connection Series (Vol. 3 & 4) are also quite good.
Cheers.