Focus on long tail keywords rather than short ones. They tend to provide quick wins at next to no cost.
So, let’s say you were a ‘boot merchant’. The likelihood is that you’re likely to achieve a high ranking for content tailored towards the keyword ‘genuine leather boots for women’ (long tail), rather than the more difficult to obtain keyword ‘womens boots’ (short tail).
Although the longtail may be less searched by web users, it is more focussed and provides more concise answers to queries. In turn, a more focused and precise answer should increase your conversion rates.