I have tried offers with $20k over asking, guaranteed offers, guaranteed money over appraisal, and lately a combination of all of those.

Rehab combined with value increase over time.

Combine that with doing a bit of legwork on your own.

I would say experiment with different combinations and see what your results are. 

Once you define your goals, you will need to research and learn about the various strategies of RE investing (BRRRR, flips, house hack, turnkey, etc.) and figure out what strategy will best fit your goals (or maybe a combination of strategies). 

When you combine a hot part of town, solid pool of tenant, and you're onsite it can't be beat.

Look into combining that equity with some more conventional loan products, or hard money lenders, etc. 

Water/sewer have a base charge so when you split to two, most likely the two bills will be more than just one combined.

It combines them in camera, throwing out the over and under exposed parts.  

I think a good strategy is to diversify with a combination of Suburban Cashflow properties with a few city properties that have high potential for appreciation, equity and rent increase.