I have been playing cf for like 6+ months
And I decided to roll an invoker like 3 months ago
I did it
Then I perfected spells and stuff.
I got to rank 35 kinda hard.
Then I got to rank 36
And I was there for like 3 months
I gave up after like 7th mob death or so
Then I died 3 more times.
Can ANYONE give me an advice but the permagroup one?
I used to play it like lotsa time but now it just keeps frustrating me.

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...

10 deaths isn't much in the big scheme of things.

Only you get shields, things will get considerably easier for you. If I recall correctly, that's only two more levels.

Permagrouping isn't necessary at all, and anyone who tells you it is is talking out of their arse.

Grouping, on the other hand, is pretty necessary. Invokers shouldn't find it too hard to get a group because they deal very nice damage.

Don't worry to much about mob deaths. Perhaps ask yourself why you died so many times. Are you ranking in an area with aggro mobs and repeatedly running into problems? Then don't rank there -- find somewhere else. Is your groupmate wimpying and you getting beaten down? Then tell him to warn you, or be ready to flee yourself, or don't travel with him. Are you teleporting into mobs when fleeing pk? Well, if you are close to a new level, you might want to suck up the pk death and keep your exp.