So I'm fairly new to the game, I've gotten a few things, and now I want to go play and not have a poor showing of myself. What would you build from these sets/expansions?
I have
Red Letter Core Set
Blue Letter Core Set
Tie Advanced Expansion
Tie Interceptor Expansion
Imperial Aces Expansion
Millenium Falcon Expansion
You have a lot of Squints there, which are one of my favorite ships to fly. However, with the current meta, Autothrusters are an auto-include on them. Could you borrow some or acquire 1-2 Starvipers?
Other than the Falcon, you have mostly Imperials so let's start there.
I think Vader is the Advanced pilot worth having. He can run with the pack with Squad Leader or he can take off and hit from outside firing arcs with Engine Upgrade. If he's giving away actions, let's take Omega Ace who wants to take 2 actions. Vader doesn't always need both of his and Omega has obvious benefits. Just in case Vader has is needed elsewhere, we'll give Omega Push the Limit. Automatic crits for a stress is worth it. You only have 2 dice so go after the lowest agility ships first. We'll take a cheap Saber Squad Interceptor as filler and an even cheaper Alpha Squad to give one of them a Targeting Computer which gives Vader other options for helping your squad do damage with his shared actions. We're still at 99 which gives us a good shot at Initiative.
For your Rebel list, I've got a nice one with Poe and Lando here:
As an edit to that list you may think about is switching one of their Elite Pilot Talents to Marksmanship as you have the points to do so.
Keep enjoying the game Tybrid!