The biggest lesson, which I learned early on: get clear on the type of property you want to buy, then tell everyone over and over again.

Samsung are garbage, won't buy another.

Also, consider this copy & paste advice below:Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a Class A property in Class D area, what quality of tenant will you get?

.✅ Secondly, good cause has a max cap on yearly rental increases at a certain margin above CPI or 10%, whichever is less.For those of you who own stabilized, high quality housing like we do, this shouldn’t be a problem.But instead of keeping rents flat because you are a nice person or increasing just a little bit, you could get yourself in trouble when it comes to funding future major repairs and capital expenditures.As long as you are increasing to what the market will bear, you will be in good shape.Also if you are looking at purchasing blighted, dilapidated housing with the intent of raising rents and financing improvements to the property, you will have to take this into consideration and buy accordingly and on in place rents not projected rents.On the implementation side, however that pans out, you might be able to get these necessary rent increases to finance repairs but you may need to go to housing court in order to get the green light but we are just not sure at this point and remains to be seen.✅ Thirdly, in regard to objectionable tenancy and nuisance caused by disruptive tenants, you will need to document these violations with undeniable evidence.Because police reports are not usually able to be procured due to disturbances like drug trafficking or domestic violence, you’ll need to take matters into your own hands on producing that documentation.I recommend getting security cameras installed in all common areas and outside your properties.I’ve used SimpliSafe security cameras but you’ll need to install WiFi service at your properties so that you can maintain recordings in the event of violations and add to your lease that any tampering with said cameras constitutes a lease violation as well.This is still developing and once we get further clarity, we will host a round table with legal experts on how to best protect our properties and residents.

In Atlanta, Georgia - unless you get caught doing something illegal, it's considered 'grandfathered in' and won't be a problem when buying or selling.

Look to buy off market.

I assume your question means you already have a 600k property that you owe 420k on, and are wondering if you sold that property to buy more properties which way would you come out better over time. 

BiggerPockets also has a calculator to analyze deals, and I highly recommend you start this as soon as possible, even if you are not ready to buy.

I did a DSCR cashout loan from my other rental to buy and reno.

I plan to leave them enough that they can afford to buy a house or start a nest egg, but I am not leaving large sums to them.