Have separate rooms for sample storage, extraction, PCR reaction preparation, and electrophoresis.
Keep all reagents in separate freezer from samples.
Always wipe down all working surfaces.
Avoid aerosolizing any DNA/RNA.
Use different sets of pipettors for extraction and PCR reaction setup.
Work under a PCR hood that is decontaminated by UV on daily basis.
Use aerosol-barrier tips.
Keep primers and enzymes in small aliquots so you replace them often.
If you have contamination:
Dump as many of your cheap reagents as possible.
Get acquainted with the PCR troubleshooting flow chart ---> [Only registered users see links. ]
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