Additionally, trying to spot paint even a white wall with white paint doesn't work, let alone other colors.

In some homes planting the front or placing pots could increase the curb appeal, in others it could be paint or furniture etc.

I know so many people who have been ripped off by contractors.  

Security Deposit: 2600Lease states no smoking/painting walls/no hanging things on wallsTenants have moved out and have left two truck loads of garbage to be removed.Damaged doorPainted walls which got on the ceiling and trim Lots of holes on the walls throughout the houseDamage from windows being left open constantly Weed was clearly smoked in the house (smell throughout the place) so we need to deep cleanWater bill wasn't paid so I had to turn back on utilityMissing keyQuoted costs:$450 junk removal (some furniture)$935 for damaged doors/windows, painting cleaning$30 for utility turn onTenants were only there for a year before moving out so a lot of this is beyond normal wear and tear. 

I'm a pretty handy guy but this would be outside of my realm, but my experience helps me understand how much this type of improvement should cost.Improvements: remodel kitchen and bathroom, paint interior, fix exterior scafolding.How should I go about finding a contractor?

Interior remodel, paint, floor, appliances, fixtures, etc Lessons learned?

Painting and flooring are super easy.

Renovated the basement unit, new roof, new soffit/ facia, new gutters, new exterior paint that was paid for by seller.

Sell, rip the bandaid

You second property will rip I bet.