Cloaked Fleet, Rejuvenator Factory, Webbed Defenses.
1 Level of: Ambush, Generalist, Subterfuge, Light Hulls, Forcefields, Engineering. Starting planet science goes to upgrading the Rejuv Factory twice, Revealer Battlestation once, and the Home Planet Station once.
This gets 3 wings of your starter fleet to Mk3, the Revealer BS's Spider and Generalist turrets to Mk3 and MLRS turrets to Mk2, and all of your home planet's metal/energy/defenses to Mk2. Picking up a level in light hulls is not only slightly cheaper than getting Ambush, Generalist, and Subterfuge to level 2, it also upgrades a ton of good pickups including Telsa Torpedo Frigates, V-Wings, Tritium Sniper Frigates, Raiders, and a lot more.
After you capture a couple more planets, getting Fusion and Disruption to level 2 would be a good choice as that will upgrade your turrets, defensive frigates, and your Agravic Pods. Alternatively you can double down on Generalist wings like Autocannons, V-Wings, and Tritium Snipers, or if you've found a bunch of Tesla Torpedo Frigates you can switch to investing heavily in Splash, or get more paralysis and engine slow from more Warbird Frigates and Spiders.