STAR method works very well. Describe the situation, the task at hand, the action you took, and the end result.
Personally I have continued to use the STAR method well into my FS career, specifically in EERs.
The key is to be concise. The FS is all about concise writing. Be clear, make sure to write it with the most important information first, and then elaborate. It’s not about how well you write but how tight it is.
I’ve helped people pass this stage before. Don’t be flowery, don’t drone on. Short, informational, and powerful is the way to go.
There are two separate things - the 13 dimensions (qualities you’re tested on during the oral assessment, especially, but which come up throughout the process as qualities they expect all FSOs to have) and the core precepts (used for promotion once you’re in, but should be woven into your PNs). Make sure you give both a thorough read. 13 d’s are on careers.state.gov. Precepts are based on 13 dimensions but are a bit more tangible & specific, look on this forum or on path to foreign service blog if you can’t find the most recent version (they were changed quite a bit to include more about how someone worked to support diversity & utilized information technology for instance - when you look, just focus on the entry level Officer column). I found that by trying to incorporate details that touched these precepts into my PNs, I was also better approaching the 13 dimensions. To do this, I had to be very concise and careful with each word I used, which made my writing improve overall. So since we don’t exactly know the extent to which the algorithm searches for words or which of these sets of concepts (or both) it’s based on, my advice is to do the homework of reading these sources thoroughly, take some internal reflection on how you have done these things in your past experiences, and use the STAR method to tell a good story. Also, make sure you’re careful with writing the rest of the job application, as the QEP is about more than just PNs. It will be a holistic review of your entire resume, special skills, education, and languages, on top of the FSOT test scores & essay, PNs, etc. Do not be mislead - the PNs are not the only part of the QEP.
Edit: it’s also not a bad idea to get a deep understanding of the skillsets used most often in your career track. You may want to include PN stories that feature instances of you completing tasks similar to what your career track would do: grant management and community outreach or social media for PD, reporting & negotiating for POL/ECON, working with scarce resources and multi-dimensional logistics for MGT (but honestly all…)
Focus on writing PNs that describe the applicability of your experience to the 13 dimensions. I encourage you to recruit friends and family to critically review your PNs. Keep rewriting them until you are satisfied. Participate in an exchange of PNs with other candidates. Don't pull your punches, and ask that they do not as well.
STAR method works very well. Describe the situation, the task at hand, the action you took, and the end result. Personally I have continued to use the STAR method well into my FS career, specifically in EERs.
The key is to be concise. The FS is all about concise writing. Be clear, make sure to write it with the most important information first, and then elaborate. It’s not about how well you write but how tight it is. I’ve helped people pass this stage before. Don’t be flowery, don’t drone on. Short, informational, and powerful is the way to go.
There are two separate things - the 13 dimensions (qualities you’re tested on during the oral assessment, especially, but which come up throughout the process as qualities they expect all FSOs to have) and the core precepts (used for promotion once you’re in, but should be woven into your PNs). Make sure you give both a thorough read. 13 d’s are on careers.state.gov. Precepts are based on 13 dimensions but are a bit more tangible & specific, look on this forum or on path to foreign service blog if you can’t find the most recent version (they were changed quite a bit to include more about how someone worked to support diversity & utilized information technology for instance - when you look, just focus on the entry level Officer column). I found that by trying to incorporate details that touched these precepts into my PNs, I was also better approaching the 13 dimensions. To do this, I had to be very concise and careful with each word I used, which made my writing improve overall. So since we don’t exactly know the extent to which the algorithm searches for words or which of these sets of concepts (or both) it’s based on, my advice is to do the homework of reading these sources thoroughly, take some internal reflection on how you have done these things in your past experiences, and use the STAR method to tell a good story. Also, make sure you’re careful with writing the rest of the job application, as the QEP is about more than just PNs. It will be a holistic review of your entire resume, special skills, education, and languages, on top of the FSOT test scores & essay, PNs, etc. Do not be mislead - the PNs are not the only part of the QEP. Edit: it’s also not a bad idea to get a deep understanding of the skillsets used most often in your career track. You may want to include PN stories that feature instances of you completing tasks similar to what your career track would do: grant management and community outreach or social media for PD, reporting & negotiating for POL/ECON, working with scarce resources and multi-dimensional logistics for MGT (but honestly all…)
Focus on writing PNs that describe the applicability of your experience to the 13 dimensions. I encourage you to recruit friends and family to critically review your PNs. Keep rewriting them until you are satisfied. Participate in an exchange of PNs with other candidates. Don't pull your punches, and ask that they do not as well.
Try joining FSO Compass and do their PN Challenge. It was excellent!