There will probably be other members with varied ideas on this, but I'll add my view on it for what it's worth.

One question....are you formulating your own price with the ratings or are you just ranking them in order of what you think the chances are.

If you're betting to prices, the best way to go with the win betting is to wait until you see something that is a double overlay on your rated price. Otherwise you'd be dutch betting 4 to 6 runners which I don't recommend really.

I.E. You rated at 6/1 and you are able to obtain 12/1.

WIN STAKING -

Probably 1% of your bank level stakes and review it again once your bank doubles.
You want to start of conservatively as you can experience horror runs as everyone does from time to time, and especially when it's a newly formulated plan.
Let's say your bank is hypothetically $100.
Bet $1.00 until your bank reaches $200 and then bet $2.00.
You might think it's way too conservative, but if your ratings are accurate, your bank will double and compound very quickly.
If you find you have a run of outs and have to fine tune your ratings, you'll last 100 bets before your bank is gone.
If you bet 10% of your bank you'll be bankrupt (hypothetically) after ten losing bets!
When your bank is gone entirely, up will bob five or six good priced winners.
Invariably it happens.
It's not Murphy's Law - It's the punter's lament.

As far as multiple bets go, now this is not an are where I am entirely up to speed with, but I would again suggest a careful and cautious approach.
Remember there's always more races tomorrow, if your bank is gone you have no chance.

If you're talking Trifecta's I'd probably go the value way as favourites in the top two placings decimate any real returns unless a bolter fills the placings and I'd suggest if it's a "real" bolter, you won't have it high in the ratings anyhow.

Good Luck Testarossa, let us know how it goes - I'm sure others on the forum will have other views to put forward, maybe you could be selective and take pieces from everyone who replies to suit your own style.
There's always more than one way to approach something.