spell shield vs attack of oppertunity

My favorite class in pathfinder is a Magus. I’m considering playing a reckless, dex-based, magus who regulary carries out combat maneuvers. However I don’t want to allocate so many feats to improved combat maneuvers just so I can avoid attacks of oppertunity. I know spell shield won’t take away the risk entirely but in general, how effective would it be at reducing the chances of recieving a hit from an attack of oppertunity?

Relivant stats: the players are starting at level 7. my inteligence is +4.(+5, next level) my dex is +3. My AC is 21 – 25 after applying my Int from spell shield. I’ll also be upgrading to medium armor soon after the campaign starts. I have weapon finess so I can use Dex on attack rolls, (inclucding combat maneuver, attack rolls)