Obvious choices: Spell Focus - Conjuration and Augment Summoning.
Don't waste your time with - Spell Penetration and Greater Spell Penetration. As a conjurer most of your attack spells bypass spell resistance, as do your summoned monsters.
Don't overlook - protection from XYZ spells, on the other guys. Be ready to remove them with a dispel so your monsters can chew up the bad guys, or scour your monster lists for those things you can summon that have ranged attacks (lantern archons, for example). Also don't forget the other abilities of your summons (special movement modes, protection from evil auras, and so forth).
For getting your summons off successfully, I really like Rapid Spell (get your summons off without waiting to be disrupted). I'm also a big fan of metamagic rods of Empower or Maximize to get more monsters out of your summon spells (the 1d3 or 1d4+1 smaller monsters are often a great deal, and if you can empower or maximize the number, so much the better).
If you're not going to make extensive use of Rapid Spell, do not give up illusion. Greater Invisibility is your friend. Or any other method to avoid getting disrupted during your summoning.
As a Chaotic Neutral summoner, you should look into the Alienist prestige class from Complete Arcane, if you haven't done so already.
Since you're sinking a feat into spell focus - conjuration, you can take advantage of it by using other conjuration spells that actually have saves, such as grease, glitterdust, or blast of flame. In particular, if you're starting at first level, grease should probably be your 1st level conjuration, not summon monster I. You can also look at taking the archmage prestige class at high levels, since you're already on the path of the qualifications.
Learn languages so you can communicate with the things you summon. Celestial, Infernal, Abyssal, Auran, Aquan, Terran, and Ignan.
Finally, there will be times when you're going to want to do damage directly rather than with monsters - that may be fairly often, or it may be rare depending on your character's mindset. If it's going to be often, consider sinking resources into ranged attacks with a good dexterity score and perhaps point blank and precise shot. The conjuration attack spells include a lot of ranged touch spells (and making good use of those make evocation a good barred school).