Simple Break down.
Buy the following skills:
Read/Write
Read Magic
Wield Magic
Magic Sensitive (5pt Merit)
He will then want to buy at least a couple 1st tier spell slots, and probably a 2nd tier (they build in pyramid formation. So 2 1st before you can buy a 2nd, 2 2nd's before you can buy a 3rd).
After that spell power gives you more spell points (lets you cast more spells). Spell Intensity lets your spells do more damage. I normally advise new mages to buy power over intensity UNLESS they are playing an evocation style mage. Then you want to balance the 2 out.
Other suggestions:
Buy level 1 in a weapon skill. You will probably run out of spell points, having a weapon to fall back on is important even if you just have level 1.
Level 1 sense magic is useful if you can spare the few points for it.
Dont worry about getting 3rd tier spells till later.
Look over the incants for casting spells and make sure you understand them. This is vital for combat mages, less vital for out of combat casters (diviners, shield mages, etc)
Once you get into game. Find a mage, ask them for help IN-GAME. Some characters are assholes (Dietrich!), other characters are Philanthropists, but most are generally nice people who will answer questions but may not give you all the "nifty tricks", but if you can find a mage who does the type of stuff you want to do...watch them and see what they do...then ask how later and maybe they will reveal a few secrets if you play it right.

If you have any other questions let me know.
-E