New landlords rarely fail from one catastrophe; they bleed from predictable, avoidable wounds. The seven below are the ones we see most, priced in real dollars: gut-feel pricing (−$1,200/yr), casual screening (−$5,000 to −$10,000 per bad tenancy), internet-template leases, deposit-law violations (double damages), deferred maintenance (a $150 leak becoming a $4,000 repair), do-it-yourself evictions done wrong, and owning with zero reserves. Every one has a cheap prevention. That is the entire economics of doing this well.
I. Pricing the Rent by Gut Feel — costs $600–$1,800 a year
Price $100 over market and the home sits vacant an extra month ($2,400 gone on a typical rental); price $100 under and you donate $1,200 a year, forever, compounding at every renewal. The fix costs nothing: a written comparative analysis of actual leased — not listed — comparables before every listing and renewal. The vacancy ledger in our worth-it essay shows why this single discipline outweighs the entire management fee.
II. Casual Screening — costs $5,000–$10,000 per bad tenancy
The expensive tenant almost never looks expensive at the showing. Rigorous screening — credit, verified income at a multiple of rent, eviction history, prior-landlord references, applied uniformly to every applicant (which is also your fair-housing shield) — is the highest-return hour in the entire business. Skipping it to fill a vacancy faster is trading a $2,400 problem for a $8,000 one.
III. The Internet-Template Lease
A generic download doesn't speak Pennsylvania: deposit handling, notice provisions, utility responsibility, and required disclosures differ by state, and the gaps surface precisely when the relationship sours — the one moment the document is all you have. A PA-specific lease reviewed once by a local attorney costs a few hundred dollars and amortizes over every tenancy you'll ever sign.
IV. Treating the Deposit Like Your Money
Pennsylvania's deposit rules carry real penalties — including double damages for a blown 30-day return. The complete framework is in our deposit-law guide; the one-sentence version is: caps, escrow, itemized list, thirty days, no exceptions.
V. Deferring the Small Repair — turns $150 into $4,000
Maintenance compounds like debt. The $150 supply-line drip becomes saturated drywall, becomes mold remediation, becomes a vacancy during repairs. Fast response isn't tenant-pampering; it's capital preservation — and it's the quiet reason well-managed homes carry higher renewal rates, which is itself vacancy prevention.
VI. The Do-It-Yourself Eviction
Changing locks, removing doors, shutting utilities — Pennsylvania treats self-help eviction as unlawful, and it can convert a non-paying tenant into a plaintiff. The lawful path through notice and the magisterial district court is slower and cheaper than the shortcut's consequences. Rare by design, lawful when required — that's the professional posture.
VII. Owning With Zero Reserves
The water heater does not consult your checking account. Professionals hold three to six months of rent per door; owners without reserves make their worst decisions — panic tenants, deferred repairs, credit-card capital — at the exact moments good judgment pays most. If building that buffer feels impossible, the honest conclusion may be that the property is over-leveraged, which is worth knowing early.
The Pattern Behind All Seven
Every mistake on this list is a system failure, not an intelligence failure — smart owners make all seven when they run the property from memory and mood. The prevention is boring: written pricing analysis, written screening criteria, a real lease, a deposit procedure, a maintenance response standard, a legal process, a reserve target. Whether you build that system yourself or rent ours for 8%, the point is that it exists in writing before the first tenant does.
This essay is general information for Pennsylvania rental owners as of September 2026, not legal, tax, or financial advice. Statutes and tax rules change and carry exceptions — confirm current requirements with a Pennsylvania attorney and your tax advisor.