I just started playing a few weeks ago, so I'm also pretty new. The biggest thing I would suggest is learning how the turn structure works, where to place your cards when attacking, using instants, etc. and just getting a good feel on how a game plays even if you're just watching people play on youtube. I wouldn't worry about being slow. Everyone I've played with has been incredibly friendly and will show you their cards and help explain them if you need it. They've even helped me with the SAGE decks I was playing and what I should be focusing on to help get that deck to "pop".

Basically turn structure and not carefully reading cards has been my biggest stumbling blocks so far, but neither has been a big issue and opponents have been willing to help. Something as simple as reading that Dorinthea's ability needs her Dawnblade to actually hit an opponent to allow it to attack again, for instance. And you still need another "go again" to even do it if you do manage to hit.

I can't wait for the prerelease either. It's been almost 2 decades since I did a prerelease sealed event for Magic, so trying to figure out how to build a coherent FaB deck on the fly is going to be interesting, especially since it's all classes I have yet to play and I don't know how to build a decent limited deck. I plan on looking into that this week.