1)Relevance
The keywords should reflect what the contents going to be about or even your products/services. Relevance is important because if you are a coffee company you shouldn’t just have beans as a keyword because that is too broad and irrelevant to coffee beans.
2)Traffic
Different keywords can bring you different amounts and/or kinds of traffic. To boast the traffic of your site through keywords make sure to keep up with trends and the different ways people are going to look up your product. Again with the coffee example you would want keywords that look like, #coffee #coffeebeans #fresh. These are all different examples that might boast traffic.
3)Low Competition
For this key factor you want to use some creativity. First you research your competitors keywords and make sure you are not copying their exact words. You then want to use your creativity combined with the last 2 steps and start making new, relevant, traffic-abound keywords.