A wits is probably enough, if not, get tenacity boots. You don't want to take even trades with her until your W is level 4 or 5. By that time you'll win trades pretty easily even if you're even in gold. Before that though, you'll have to pick your trades well. If Akali uses her q to farm pre-6, go in for a stun and a few W autos before she shrouds or before her Q is back up.