Heres a handy site to check any ideas one may have about following tipping services.
This one is UK based but the stats will be similar to Aust services.

WIN BETTING
What I found , is that the profits were dramatically improved on all that had 100+ selections if 100% overlay was used.

This means if rated at by tipster at 2/1, one only backs it if paying 4/1 at jump time.

In Aust where we use Decimal odds, this is the proper way of working out a double overlay prices.

We add the 2 prices together then subtract 1 = Double overlay price.
$3.00 + $3.00 = 6 - 1 = $5.00 is the double overlay amount.
Not $6.00 as many would think.

It took most rating services results from -5% to +10%
to +50 & 100% POT once the 100% overlay was added.

This tells us if we bet any selection services top selection, preferable 6 of them at once & bet all their top selections that are double the odds that they are rated at , one should clean up.

LAY BETTING
The lay tipsters were struggling to break even with most at 3% POT & less.
Once a price filter was added between 1/2 ($1.50) - 2/1 (3.00) Min & Max.
Their results improved dramatically to approx 7%+ POT.

racing-index.com/tipsters/tipster-performance.php

It shows that it is more profitable to target win betting than it is lay betting.

Cheers.

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Cheers.

Don't really understand lay betting, but I do know that there is no such thing as a free lunch!! they seem to work at about 105% or so, then take 5% commision, so where does that leave you in the long run?? or have I missed it completely?