run the primers here

http://biotools.nubic.northwestern.edu/OligoCalc.html

and try to avoid any interaction on the self-complementarity option (redesign the primers if necessary)

for interactions among primers, run them here

https://strbase.nist.gov/AutoDimerHomepage/AutoDimerProgramHomepage.htm

Self complementarity should be low (try to get score less than 4). You can run the primers on gene runner software to check any dimers, hairpin loop etc.

You can check your primers on Insilico PCR online for desired product.

If you can, set it for 1. 3 is accepted as well.

Generally, the lower self complementary score is better. The optimum self complementarity ranges from 2 to 6, and self 3' complementarity from 0 to 3.

You may check your primers for primer dimer or hairpin formation in Geneious Prime, or Oligo7 software or in online programs such as:

https://www.thermofisher.com/de/de/home/brands/thermo-scientific/molecular-biology/molecular-biology-learning-center/molecular-biology-resource-library/thermo-scientific-web-tools/multiple-primer-analyzer.html

http://www.molbiotools.com/primerinspector.php

https://www.idtdna.com/calc/analyzer/

http://www.oligoevaluator.com/LoginServlet

Hope this helps.

Thank you all for your time and suggestions.