That's where the "70% rule" comes in. 

This led me to think about what the best way is to estimate land value apart from the value of any improvements.

City websites and websites such as https://www.niche.com/places-to-live/search/safest...Do you happen to have any rule of thumb ?

I very want to emphasize the fact that, as with many tenant related improvements, making something foolproof is sometimes as important as anything else you do.

I would wait until your tenant leaves before making those kinds of improvements.

You say squatter but the law may view him as a tenant and there may be different rules you have to follow depending on which.

The lease payment replaces the electric bill, often with a lower amount, so from a cashflow angle it usually improves the customers position.

We just had our own personal door code and it makes us feel a lot safer with guests in the house.One of the best things we did when screening guests is we would send them a "welcome message" which reinterated rules such as-Don't park in the driveway-Take your shoes off at the door-etc.and hidden (smack dab in the middle) was the "secret code phrase" that they had to reply with to confirm they actually read the welcome message.

@Dan Handford I've not syndicated anything yet so this is just from a multi-family investment perspective.1) How much/what level to improve a value-add property.

More complex flips will require a GC on board and your lender will have a list of those willing to comply by the rules.