| For stats...ouch. Good warrior stats, not even a single 15 is going to be rough for a caster...
Str 10 (or swap with wis)
Dex 13 (or swap with int*)
Con 14
Int 10
Wis 7
Cha 14
*And if you plan to EVER raise int from 13 to 14 (nonmagically), just put a 14 in int to start, and 13 into con. Skill points aren't retroactive. Otherwis,e all levle up points ot charisma, and get +2/4/6 items for it ASAP.
I'd recommend starting in one of the classes 2 levels, rather than starting out spread thin. Since warlock gets better HD and (I think?) more skill points, start as Warlock 2.
For invocations, I always like Eldritch Spear + the spider climb one. If there are walls to climb on, many enemies become nearly helpless against you, or at least are unable to strike back at you. Obviously you trade out spider climb once you can get fell flight. Or...I guess sorcerer can give you flight, up to you. If using sorcerer for it, be sure to eventually swap out Fly when you can get Flight of the Dragon.
Lots of good invocation choices, though. The eldritch essences to sicken or shake are useful early on, too. I would avoid melee entirely. Hideous Blow won't make up for your crap AC and low hp in a melee fight. If you're really worried about it, be a human (if you weren't doing that already) and take the Able Learner feat (Races of Destiny) so you can buy your tumble ranks at a cheaper cost. In fact, sorcerer and warlock don't give a great skill selection anyway, so the feat might be useful for getting a bunch of skills.
Don't know what to say for gear. Maybe masterwork armor and shield. | 
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