This will be my first 4e character since the 1st edition D&D years ago. Any help on how to beef up AC on a 1st lvl Eladrin Wizard? I'm worried he'll be hit pretty easily.
Well, to beef up AC, start with Int 18 or 20, that will start you off with AC 14 or 15. Take Staff of Defense class feature, that's another +1 AC. Take Unarmored Agility or Leather Armor Proficiency, for +2 AC. So that's as much as AC 18 at lvl 1, as good as plate armour without a shield. Adding in magic items, there's the Staff of Ultimate Defense, lvl 3 magic item, +1 AC per plus if you have Staff of Defense class feature. Magic robes or leather armour will beef up your AC as well.
If your eladrin has Str 13 & Con 13, you can take leather armour proficiency and then chain proficiency and Eladrin Chain is a good item to have because if beefs up your teleports.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.