For all the flippers out there what do your percentages look like.

Myself and a friend are looking to get into investing in buying hold single-family homes. She would be putting all the cash down for the property and I'm a contractor and would take care of all of the rehab work along...

I recommend you do this annually to adjust for utility increases and other variables.

These %percentages are market dependant.  

My wife and I have overhauled our personal budget to reflect the 'pay yourself first' approach (allocate in order: income comes in -> invest -> donate -> fixed expenses -> variable expenses -> fun $$).We are looking to see what experienced people generally recommend for a holding tank for that 'invest' allocation while we target our first real estate deal.What financial vehicles have you guys used that works well for this?

The "variables" you speak to could mean this is worth every cent of a 5.4% cap rate to "I wouldn't touch this for a 12 cap".  

If I used the HELOC, the investment needs to generate >9%.I recognize there are many variables not listed here but would love to hear from more experienced investors on more generally how you think about using cash vs. home equity to grow your portfolio in the current environment. 

I question what percentage of those who invest in RE unleveraged actually understand the numbers and how extensive their underwriting effort.  

To estimate expenses, consider setting aside a percentage for management fees, plus costs for cleaning and utilities.

I will give you my numbers since we are 3 years into Velocity Banking.Home was purchased at $410k.Interest rate: 3.125%30 year termMortgage payment is around $1950 (includes insurance and property tax)HELOC: 8.25% Variable rate - current rateCredit Limit: $97kLet's say I made $10k a month and our expenses were $6k each month including the mortgage.