Sounds odd and even a bit chicken and egg but traffic is a ranking signal. The more traffic your site gets the more popular it will appear to Google and so it will be given a extra ranking power.
So what does this mean in practice. Well you should make sure all your other SEO is up to scratch first but if low traffic is still a factor you need to look at why.
Maybe there is just so little search for your target keyword that you are getting no traffic. Maybe you are down on page 6 of the SERPs and no-one is seeing you anyway. If you are on Page One or Two maybe your SERPS result is not encouraging people to click through to your site.
Take a look at it and your competitors results. Are theirs more interesting or exciting than yours? If so beef up your meta description with a call to action or something your searchers are looking for.
If you are not on page one or low on page one and traffic is very low then you may need to give it a boost and see if it helps your rankings.
Try link exchanges to increase traffic (remember to no-follow the links) .
Try creating a few YouTube videos and linking back to your site.
You could even buy some traffic. You can get very low cost traffic just search Google. This traffic will be low quality and will not convert so don’t expect it to. You are doing this simply to improve your search results