What EV should I aim for when using HP?

The short answer is always to follow the highest EV.

The long answer is anywhere from +5 to +8 depending on the promotion, and -3 on a mug bet. You can aim slightly lower if you are not mugging. The reason for this is that if we place a +8 bet and a -3 bet, then over our mug to promotion ratio we are walking away with $5 of EV each pair. By averaging $5 over the long term you will make profit.

Extra Tips:

A lower number of runners means to aim for a higher EV.

Commission will impact EV when laying, so higher percentages will lower the EV.

Cash back promotions will have higher EV as the return is higher.