I have this idea of a marksman who uses summoned creatures to fight with him and illusion to control or stop melee attackers... but the last part does not seem to work well. First, the charm spell you get only affects up to lvl 2 mobs, which is very low and Illusion seems hard to lvl (like restoration). Is illusion worth it for the play style that I want ?
I want to enjoy myself and not have to grind this skill just to be able to learn a higher lvl to make it useful...
Basically, it's a dark elf with the following
Major skills
marksman
sneak
conjuration
restoration
illusion
security
athletics
with Apprentice birth-sign
I'd personally drop Athletics, as it's impossible to control your levelling with it, but I'm not going to offer levelling advice as there are many different ways, and I use but one.
I like your Dunmer + Apprentice, although, I like it for the weakness it provides a character. If that's what you were going for, great. If not, you could make do with the Mage birthsign, as Illusion/Conjuration based magic is rather efficient.
Illusion hard to level? Just spam cast Starlight, and it'll shoot up. That is, if you don't care about levelling.
Other than that, there is plenty of excellent advice above, that I won't bother with repeating.
Edit: I just wanted to say what I think about Illusion/Conjuration and Restoration. They're fantastic. My Healer uses those schools mainly (along with Mysticism and Alteration for utilities), and gets by fine. You can summon a helper, buff said helper, and then turn invisible while your helper rips everyone apart thanks to their super health/strength/shield/whatever.
Stick with it, and you may find that you don't even need to use Marksman anymore :thumbsup: