Tom Kyte makes an excellent point about writing in clear, plain, conversational English - but then spoils it for me by summing it up as "write like you talk".
Or is it?
For one thing, what should the corrected version be? "Write as you talk" would be ambiguous, because it might mean "write while you talk". "Write the way you talk" is better, but I have to admit that it is longer and loses some of its immediacy. And nobody would want to correct The Smiths' "I am human and I need to be loved, just like anybody else does", let alone Elvis when he sings "I guess I'll never know the reason why you love me like you do." Hell, when you're the King, you can mix prepositions and conjunctions whenever you damn well please.
Of course, song lyrics have their own rules, and we have to grant some poetic license. Toots and the Maytalls' "Reggae Has Got Soul" just wouldn't be the same. But does that mean we should allow the advertisers of Dove shower gel to claim that it won't dry your skin like soap can?
Dictionary.com's definition includes this:
Usage Note: Writers since Chaucer's time have used like as a conjunction, but 19th-century and 20th-century critics have been so vehement in their condemnations of this usage that a writer who uses the construction in formal style risks being accused of illiteracy or worse.
I also can't help thinking that the French language does not seem to be weakened greatly by having to make do with the same word in Écrire comme on parle and Voler comme un oiseau. Italian is the same.
In the end, my advice is to write the way you talk.
Unless you're Elvis.