Okay
I play now the third time this game... but I didn't know if I'm now "an experient player"

...I didn't know what you except from a experient player
For me, IMO, combine some Skills is a pure personal chooice!
But from what I experienced and from what I readed on this forum (try to use some time on this forum the Search-button, handy, there is a lot written about such things like this !!

) :
Mage Skills I used are: Magic Blast, Fireball and later on Firewall for sure, great powerful skill! Combine this with Confusion and Destruction and your spells are even more powerful!
I find the Rangerskill "Ranger Stealth fantastic for all kind of character. Find some bow and focus on an enemy from a longer distance with Ranger Stealth and more: on that moment you can choose to use the bow OR use a spell like Magic Blast or Magic Missile or another spell you can use from afar.
I sometimes also use dual whielding, but most of all I play with a Bow or a Two-handed Sword in combination with spells. You can say that I'm a "Archer Mage" or a "Battle Mage" or something between both types ... That are simpy my favorite types I play with.

And if I find some gear with a skillpoint on, I try it out and I didn't sell that kind of gear! But it's a personal thing.