Pick some enemy group and make it your personal duty to wipe them out. I generally choose rogue witches, wizards, and vampires as a battlemage (which is what I'm playing currently). Make a backstory for your character before you start, even if you don't like to RP or don't know a lot of lore, if you've played through Skyrim once, you know enough. This gives you motivations to do stuff, and once you have a backstory, you can play the character and make choices organically as you play based off what he/she would do in that situation.
Other than that, I would use a skill calculator to plan out your perk selection and give you this advice. First, don't choose both destruction and archery. Figure out which one you want and go off of that. In fact, choose what kind of magic you want to use to begin with, offensive, defensive, or supportive. Offensive probably go destruction and conjuration. Defensive go Alteration and Restoration. Supportive go Illusion and Encanting. Or, choose two and mix and match. As a battlemage, I find it most effective to invest heavily in only 2 to 3 schools of magic. Past that you are fundamentally a pure mage.