Rake is essentially a dps loss when compared to mangle it costs 5 energy less but the bleed portion of it can’t crit only the initial hit so don’t use it.
Good rule of thumb is just mangle and fbite at 5 combo points or if the mob has enough hp to eat a full rip then do that instead.
And ofc I have to say this since you did not mention it always start with feral faerie fire, opening from stealth has no real advantages to it but you can do it if it feels cool or something.