Get a mirror for your shower.
I’ve always shaved at the bathroom sink before taking a shower. I tried a few times to do it afterwards but found my skin would get irritated by the soap or foam I was using, and I always felt kind slimy afterwards. I tried shaving in the shower, but was always concerned that the spicules of beard-hair would find their way into somewhere undesirable… plus I always did a lousy job because I couldn’t see what the hell I was doing. Missing spots, overdoing spots, cutting yourself. Not cool.
After installing a mirror, I can’t recommend it highly enough. That whole spicule thing might still be a concern, I’m not really sure, but the speed, ease, and convenience of shaving in the shower can’t be overstated. Constant lubrication, constant rinse, and accuracy comparable to pre- or post-shower shaving in front of a larger mirror. Fog-proof your new in-shower buddy (or bring it up to temperature under the running water to prevent fogging) and you have yourself a gay old time.