I feel this. I haven't been able to get a good foothold in the Drift yet, I get my teeth kicked in by a lot of things still. I'm wary of doing the Iso vaults because of that. I don't know what I need to change to make it better, but it's really put me off of Warframe as a whole.
I've honestly found Iso Vaults are sometimes easier than the actual Cambion Drift bounties. IMO not the same learning curve of Eidolons vs. regular Plains Bounties.
I'd try the first Iso Vault to get your foot in the door, the extra Mother tokens don't hurt either