There are three tricks to beefing wizard damage.
The first is simple: Hit Moar Guyz, kthx. Basically, the wizard excells at the at-wills that hit multiple targets.
The second is: Don't use items, powers, or feats that aren't geared towards Moar Damage and expect to deal Moar Damage. Magic Missile sucked, and it sucks now as a damaging power.
The third is: Wizard dailies are game-changers. Use them to make your turns more efficient and potent.
With the ranger in contrast, they have a super-effective at-will in Twin-Strike, but they don't have the same level of daily KAPOW. That's fine, most strikers are supposed to be about consistant damage, rather than burst.
So... you go Fire Wizard. Go Human (extra feat yo), and go 20 Int. +5 to hit, +5 to damage is awesomazing. Then your three feats (1st and 2nd level + human) could be... Wand Expertise, Dual Implement Spellcaster, Superior Implement Proficiency (cinder wand). Then your implements of choice are... oh... a master's wand of scorching burst... and... oh... who cares, a +1 something of whatever. Doesn't matter for this.
This makes the following happen:
Wand Expertise +1 to hit.
DIS +1 to damage
cinder wand +2 to damage with fire
master's wand of scorching burst: +1d6 damage to enemy in origin square of scorching burst
20 Int +5 hit, +5 damage
This becomes a total of:
+8 to hit Reflexes, for 2d6+9 damage on a single target, 1d6+9 against multiple targets not in the center. Then, should any one of those crit (cause crits occur more when you roll dice more), that enemy will instead take 15+1d6+1d10 damage, or if they are at the center, 21+1d6+1d10 damage.
Fourth edition is really easy to get more damage out of any character class, with the simple fundamental of: To do more damage, take character options that do more damage.