Falling Icicle
Adventurer
The strongheart halfling is a great race choice for warlocks. They get a bonus feat (which you could use on Luck of Heroes, to get not only the normal halfling +1 luck bonus to all saves, but a +1 to AC as well), and their small size and low strength do little to inhibit the class. Just beware of grapples. The only real big drawback is the 20 ft. base speed, but that can be made up for with boots of striding and springing. But really, almost any race can make a good warlock, even those with a Cha penalty (many warlocks don't get any invocations that have saving throws).
For invocations, some of my personal favorites are See the Unseen (who doesn't want darkvision and see invisibility all the time), Fell Flight (it lets you fly, 'nuf said) and Vitriolic Blast (the ultimate eldritch essence invocation). Other great ones are Eldritch Spear, Walk Unseen, Devour Magic and so on. But really, it just depends on what you want your warlock to be good at. If you plan to socialize, Beguiling Influence and Charm are great. If you want to be a battlefield controller, invocations like darkness and chilling tentacles might be for you. The Dead Walk is great for providing both temporary and permanent undead minions. Just make sure to get a wand of inflict light wounds so that you can heal them.
You will absolutely want to put the maximum number of ranks in Use Magic Device. This skill is essential for warlocks, who are otherwise starved for versatility. The most difficult choice you will have to make is what feats to take. Warlocks can make good use of many feats, but get very few. Point Blank Shot and Precise Shot are decent choices, but they're not necessary. Since you are making touch attacks, you can usually afford to take the -4 penalty for shooting into melee, and you can get a Rod of Magical Precision instead of the feats for 12,000 gold. The heritage feats in Complete Mage are a cool way to give flavor and some extra versatility to your character, but they will consume most of your feats. Scribe Scroll is a great choice at later levels as it lets you have access to any spell in the game, thanks to Imbue Item.
For invocations, some of my personal favorites are See the Unseen (who doesn't want darkvision and see invisibility all the time), Fell Flight (it lets you fly, 'nuf said) and Vitriolic Blast (the ultimate eldritch essence invocation). Other great ones are Eldritch Spear, Walk Unseen, Devour Magic and so on. But really, it just depends on what you want your warlock to be good at. If you plan to socialize, Beguiling Influence and Charm are great. If you want to be a battlefield controller, invocations like darkness and chilling tentacles might be for you. The Dead Walk is great for providing both temporary and permanent undead minions. Just make sure to get a wand of inflict light wounds so that you can heal them.
You will absolutely want to put the maximum number of ranks in Use Magic Device. This skill is essential for warlocks, who are otherwise starved for versatility. The most difficult choice you will have to make is what feats to take. Warlocks can make good use of many feats, but get very few. Point Blank Shot and Precise Shot are decent choices, but they're not necessary. Since you are making touch attacks, you can usually afford to take the -4 penalty for shooting into melee, and you can get a Rod of Magical Precision instead of the feats for 12,000 gold. The heritage feats in Complete Mage are a cool way to give flavor and some extra versatility to your character, but they will consume most of your feats. Scribe Scroll is a great choice at later levels as it lets you have access to any spell in the game, thanks to Imbue Item.