The time has come.
As much as I despise being bad at things, I'm new so it is what it is. All I can do is work my ass off to hopefully expedite this terrible, terrible introductory period so that I can get away from it ASAP.
I'm working on setting up my first campaign and the questions are infinite but I guess I'm just going to have to jump into the shark tank to get my feet wet even if I lose them.
I'm trying to add creatives to Decisive and I just got a note saying "NOTE: You have uploaded creative that has very low traffic volume. You may see limited or no traffic on the following sizes: 300x75" -- if I use that size am I going to get 0 conversions 110% guaranteed or should I still test? What sizes are the most ideal?
I'm going to keep going through threads and figure as much out on my own as possible. YOLO.
ps, god being new is fucking stupid #terrible

If I were you I would start with the 320x50 or 300x250.
You will be able to gather data faster and when you find something that works it's much easier to scale.
Thank you so much for the responses.
I know this introductory phase is going to be beyond agitating in terms of feeling roadblocked at times/having to learn brand new things but I vow I will bite my tongue and plow on.
Cheers.
We all go through it buddy, I just think of every mistake I make when starting out as being a learning curve. Wasted money on an incorrect tracking setup for me is an investment in my education. Just think of how much you’re learning 
Yeah, the opening "I now know what I don't know" stage sucks - I'm going through it right now in another field of business, and it's painful!
Stick it out and keep producing! You'll be at the "unconscious competence" stage before you know it.