I guess im looking to try and expand my horizens and would apprecate any advice form anyone who has LARP'ing XP.
You'll have a hard time separating yourself from your persona if you are next to your wife and you won't be able not to be yourself. I suggest that for your first one, you play in different areas and next time when you have the hang of it, you can be together. Beside, not knowing people around you will force you to interact with more people rather than just speak to your wife the whole time.
Look for a group. Your LARP most likely have a board or something similar. Look for a group needing a character with certain skills you'd like to have and join them. That way, you'll have more experienced people to help you out.
A good costume goes a long way towards making you feel like the character.
Also, you should know everything about your character, even info no one will ever ask you. What were his parents like? What's his favourite colour? What does he do for fun? Is there some expression he likes to say, etc. The more you know your character, the easier it is to play it.
On the top of my head, that's it. What kind of LARP is it anyway?