I used to get the same type of sound as Clams Casino, without actually knowing that, I mostly recently got into his production.
Here's what I used to do. Make a normal beat, tempo at about 90, find a dope sample, anything, preferred vocals, add delay, reeverb as previously said. Do anything else you would normally do to it etc.
Now export the whole thing to wav. Open up a blank fl studio project, load the beat in Edison and play it one octave lower or somewhere around that place according to preferences.
That way everything has a lowered pitch, but it still sounds natural, sometimes it actually sounds more natural than the first version.
So, thats just my way of doing it, let me know if it works for you guys.