The best rules (or dispositions) and the best actions may come apart in theory. Fortunately, a reflective agent may be able to limit the damage by means of what Ainslie (1975) calls "private side bets".
Consider Kavka's toxin puzzle. Many philosophers think that a rational person couldn't win the prize, because by the next day they would no longer have any reason to drink the toxin -- and, recognizing this, they will be presently unable to intend to so act. To be successful in situations like this, agents require the internal power to 'bootstrap' additional reasons into existence. (Note that the terms of the game specify that you're not allowed to employ external incentives to win the prize. So you can't make a bet with anyone else that would give you additional reason to follow through and drink the toxin.) Intuitively, the solution seems to be that you should just make a resolute commitment - a promise to yourself - to drink the toxin. The hope is that this internal act of self-promising will provide you with a new reason - an internal incentive - to go ahead and drink the toxin, thus allowing you to intend this action and to reap the rewards.
But can a backward-looking consideration, the fact that you made yourself a promise, really provide you with a reason to act when the time comes? Consequentialists will naturally be skeptical of this, and even deontologists may doubt whether promises to yourself can really be binding. (After all, the recipient of a promise is typically at liberty to release the promisee.) But even so, perhaps we can finagle a forward-looking reason out of this. Just consider how beneficial it is to be the sort of agent who can trust one's future selves to carry out earlier resolutions. Who knows how many more toxin puzzles or newcomb problems you'll face in future. If you renege on your self-promise now, you'll lose this valuable self-trust. Next time you sail past the Sirens, you'll have to tie yourself to the mast rather than steadfastly resisting their call. (Etc. etc.)
In short: being less trustworthy, even just to yourself, is costly. So you can bootstrap additional reasons into existence whenever you need them, just by promising yourself that you'll do this thing, thus putting your self-trust on the line. (A slightly different way to put it is that you're effectively bundling together a host of desirable actions into a single fragile disposition that you won't want to risk weakening -- depending on the precise details.)
There are obvious limitations to this approach. If the immediate gain of defecting outweighs the long-run expected cost of tarnishing your self-trust (and of weakening your general disposition to act on globally optimal rules), then you'll defect. So you won't be able to win Kafka's prize if, for example, you know that this is the last decision you'll ever make. (Cf. one-shot vs. iterated prisoner's dilemmas.)
One final move that might help further is to place some intrinsic value on being the sort of agent who sticks to resolutions and so is capable of inter-temporal coordination. I'm not sure how plausible this is, but it doesn't seem completely crazy at least. There's something appealing about this self-conception -- about seeing one's momentary selves as united in doing their bit to implement the agency of a temporally-extended whole -- rather than being self-contained islands of agency, perhaps causally related yet normatively independent and isolated from the others. [Update: In other words, the atomist adopts what Strawson calls "the objective attitude" towards himself: his other timeslices are "to be managed or handled or cured or trained", rather than to be reasoned with co-operatively.] That's not to say you should maintain your holistic self-conception at any cost, of course. But it might be a shame to give it up too cheaply.