If you are experiencing faint or no bands, try the following tips to increase band intensity:
Use the appropriate number of PCR cycles, usually the number of cycles is carried out 25-35 times, but in cases where the template concentration is low use more cycles
Optimize the extension time for successful replication of the target, for most PCR applications an extension time of 1 min/kb is sufficient
Make sure there is sufficient annealing time for primers to bind to the template
Optimize annealing temperature, primers cannot bind to the template if the temperature is too high
Use a denaturation temperature of 95 °C
Optimize the denaturation time, if the denaturation time is too long or too short, then the DNA might degrade or not completely denature, respectively
Each dNTP should have a concentration of 200 µM
Optimize your primer concentration, the concentration of each primer should range between 0.1 to 0.5 µM, but for most PCR applications 0.2 µM is sufficient
Avoid cross-contamination, contaminated dNTPS and impure water, always use fresh nuclease-free water
Make sure to use sufficient amounts of magnesium, for PCR a typical final concentration of magnesium ranges from 1 to 4 mM