Your point on deciding which sacrifices you want to make seems like good guiding words when considering different investment opportunities.

The 70% rule is a solid guide, but in competitive markets like South Florida, it’s tough to stick to—many investors adjust based on their target profit margin or risk tolerance.

The flexibility allows investors to select the coverage that aligns with their strategy and budget.When clients receive a proposal, they are guided through their coverage options by an expert team member.

Publication 15, Employer's Tax Guide, says only this much:...Payments for the services of a child under age 18 who works for their parent in a trade or business aren't subject to social security andMedicare taxes...No definition, and IRS publications are not really law anyway.

As a newbie, I need someone to guide me from the beginning to try to avoid mistakes and hopefully be very successful.

Start with BiggerPockets Ultimate Beginners Guide (free).

Either way this is just a metric to help guide you, with this tenant you already know that they are a good tenant.

Quote from @Nate Meeker: Great insight, I am personally choosing not to file these for clients, but am providing a free guide to help them.  

I have a question maybe someone can guide me to the right source,I have a client who's house I am buying, she is currently in foreclosure and refuses to rent.

Before investing here I suggest you read The Ultimate Guide to Grading Cleveland Neighborhoods to get yourself an understanding on the market.