So a few things on prof:
There's the cap, each wave is a maximum of 10 proficiency, there is sometimes a cap increasing event which increases this number.
0 hits do not give prof, some examples include attacking the spiders images and when goocidic has his physical barrier up
Rough chances of prof increase:
Attacking with weapon ~20%
Attacking with charm ~25%
Healing ~66%
You will also not gain prof for levels below or equal to your prof amount, so if you have 10 sword prof, you will not gain any from all attacks until level 11.
If you want to give yourself brain aids you can see this topic:
https://forums.d2jsp.org/topic.php?t=84248031&f=74This image gives some idea on what mob abilities do, let me know if any of it is unclear:

I would not worry about mastery though, as to get even 10 in a single area takes a long time, focus on mq'ing/killing mobs as fast as possible and take the prof as it happens. Focusing on prof is not a style of play i'd recommend.
The main bonus to solo play is you get all the drops and drops for solo generally seem to be slightly better than group climb drops.
Getting a group willing to explore is rare.
Getting a whistle climb is much easier but if you're after item drops to make fg, these are absurdly rare. I've seen about 3 decent items in about 1000 climbs, and it's still a 1 in 5 chance to get it. I see something of that quality in solo more like 1 in every 50 climbs