
spalding |

That abjuration(counterspell) subschool is a nice place to start as it gives improved counterspell to you for free as well as the ability to several times a day do a counter spell as an immediate action.
If you want to ready actions to counter spell then you'll want quicken spell and rods of quicken spell to allow you to cast during your turn and still have the standard action to spend for the readied action.
There is a headband that helps with counterspelling as well as it gives you an immediate action counter spell once per day, it's in the ultimate equipment guide (but this means you can't wear a headband of intelligence).
Rings of counterspelling and contingency aren't bad options either to help you be ready to counter more options too.
However often times being proactive is better -- if you can layer defenses and prevent casting to start with that tends to work better.

Salindurthas |

Well, Destructive Dispel might help you out. The action you invest in a counterspell can stun or sicken the targeted spellcaster.
Dispel Magic is an obvious choice, since it lets you counterspell anything, although it requires a check. You probably already knew that one, however.
Since counterspelling is a Caster Level check, boosting your caster level would be nice.
Strength of the Land will help if you are a Dwarf.
Gifted Adept is another choice, although whether you'd choose this for Dispel Magic or Greater Dispel Magic might be a tough choice.
They are both magic traits, so you can only choose one, unfortunately.