I need some adviceFollow

I have levelled my mage to 13 and have been enjoying it. Suddenly though its harder than it was. What should my basic tactics be at this early stage. I have been opening with Frost Bolt to slow them down then a few fireballs followed by FireBlast.....doesnt seem to be working as well anymore......am i doing it wrong or is it just a flat spot that will pick up in a level or two?

I was just where you are - my mage is only level 26. All I can say from my experience is don't forget to frost nova if they aren't dead after that fire blast so you can back up and hit them again without them hitting you, and try not to fight more than one mob for a couple of levels. Things started to open up for me around 20 when some of talents started taking off. I'm speccing fire and even my meager 5% crit chance makes a huge difference now that ignite is all filled in. I cannot express in words just how satisfying it is to watch a mob run around on fire. Um, but maybe that's just me.

It's also been helpful to me to move between zones and focus on green quests at the early levels - much faster leveling during a phase you really don't want to linger in.