You’d don’t have a lot of options when trying to break a cover.  You’re trying to get into different wind than your opponent, but if he’s matching your moves, there’s not much you can do.  You can try to start a tacking duel.  This involves continuously tacking to try to get away from your opponent thereby forcing him to continuously tack as well.  The hope is that you can tack better than he can.  However, all these tacks are slow, so don’t let the rest of the fleet sail by you if you’re trying to beat them too.