Getting in the swing of Warframe

So. With the update, I've also been gone a year..since nightwave 6 I believe was relevant. Apparently since then they've released Protea prime, wisp Prime and several new frames and weapons I've never heard of. So. Honestly...where do I pick up? There's so much unfinished tasks/projects it feels a bit overwhelming but I don't want to fall behind the relevant marker especially when plat farming