Invokers are very fragile before you get your shields. All mages are for the most part. Typically, the easiest way to die as an invoker is by hitting a group of mob's with an area spell, or to get a mob auto-assisting onto you. Like I said, you're pretty fragile.

I've played several invokers to hero, and typically will never die in pk (because I play like a scared kitten), and only take one or two mob-deaths on the way to hero.

1) Never use area spells in places where mob's wander.
2) Never leave auto-assist on. Let the fight start, then turn it on to engage the correct beastie.
3) Do not use targeted spells. Meaning let auto-assist pull you into the fight, then do not use a name argument when casting. This will prevent you from over-spamming spells and getting dragged into a new mob and being the tank.

Not much advice, but it's the best I have. I typically have a pitiful link, so I always run on the assumption that my link is going to fail.

...Rome...