Treatmonk's God Wizard guide is good for long term. Heck, it's good for any term really.
"Save or suck" spellcasters are generally disliked. They're too binary. Either you're useless because your spells do nothing or you anticlimactically end combats by yourself. In either case, most parties will dislike you. At least the God Wizard lets his allies finish the fight or can choose to use summoned monsters to fight and provide flanking buddies.
The best save-or-lose character is probably the witch (in general), so many of the witch guides will be helpful on how these things work. In particular, The Witch's Guide to Shutting Down Enemies is a good description of how the tactics work.
Quick suggestions : use the following spells: Ill Omen, Ray of Sickening, Bestow Curse, Enervation. Have your party bard use the Intimidate skill on the baddies (if he's got the Dazzling Display feat, it's quite effective). Then go to town with your capstone spell -- I like Baleful Polymorph for the flavor but there are lots out there. I'd actually recommend picking three finishing spells, one targeting Fortitude, one Will, and one Reflex, so that you have options.
At lower levels, Blindness/Hold Person/Web may be your best options.
Icy Prison is a really good save and lose or lose.
Surprisingly, I think Illusions are a great school for save or lose spells. At low level, you get Color Spray. At higher levels, you can emulate all kinds of save or suck spells with Shadow Conjuration or take out multiple enemies with Phantasmal Web. Rainbow Pattern can end fights before they even start. Scintillating Pattern can mess up groups of weaker enemies pretty badly. The occasional persistent Phantasmal Killer can be fun, too.
Works best with a gnome arcane sorc and a robe of arcane heritage for a +5 DC to illusion at level 11 (with greater spell focus). But a Wizard Illusionist should be decent enough by using more meta magic.
Obtain an improved familiar with use magical device (or somehow gain a witch follower) to always cast Ill Omen from a wand on your next target. This makes the target roll their saving throw twice and use the worse of the two d20 results. The best part, there is no save for the bad luck effect. For example, if there was a 20% chance the big bad guy would fail their save, with Ill Omen, you have now increased the chance to 36% that they fail their save.
Treatmonk doesn't do save or lose, and I'm already committed to wizard. I guess I will have to do my own dang research. Oh well. I will take a look at the witch guide anyway, there may be some points that will help.
I wasn't suggesting that you not play a wizard. I was simply pointing out that witch tactics are save-or-suck tactics, so anything that tells you how to play a witch will implicitly tell you how to play a SoS wizard, or for that matter a SoS oracle.,...
Slow in my opinoon is one of the best spells for that. Works almost 100% of enemies, and the group can still play the battle.
Up until the release of the Bestiary IV, flesh to stone was THE go-to spell for save or lose. So few creatures were immune to it, and jacking up the DCs for it is a walk in the park.
I have an earth sorcerer character in my Crazy Character Gallery named Yiankuun Lee that can force three DC 34 saves against petrification in one round. During the Bestiary II days, my GM and I ran her in a playtest against subsequent CR encounters ranging from CR 10 to CR 25. She beat all of them except for the mithral golem (whom she was forced to flee from) and the Jabberwocky, whom she was able to kill, but only at the cost of her own life.