Does anybody assign proportions of their betting Bank towards various Wagers?

I am a very very nervous Punter and bet ridiculously small percentages of my Bank on races.
I am considering applying some sort of Formula to determine how much to invest.

I'm thinking that 1% of my Bank per Race is the maximum.
And I'm thinking a percentage of that amount depending on how good I feel about deciphering the relevant Form Factors, or in other words , how confident I am in my selections.

But how do I invest that worked out amount?
Win, Quinella Trifecta?
How much of my designated amount goes into each Pool and which pools do I invest in?
I'm not looking for a staking Plan where the wager is determined by the outcome of the previous wager.