Growl basses aren't super difficult. The basis of it is a sine wave being modulated by a formant wave. From there you can really just experiment with other settings to your satisfaction. For some examples you can open up some of my tracks that have growls in them and see some of the things I did.
As for effects, I'd recommend Tube (of course), light Stereo Detune, and a little bit of Phaser and Reverb. Again, you can experiment to your liking with other effects.