Knowing your keywords beforehand is always helpful. While keywords do not influence my personal finance and investing topics and arguments, they do influence wording choices. It is not always obvious how people search, so it is worth checking when you write.
There is a very lightweight way to do this. Once you have decided what to write about and have a written or mental outline, then go to the Adwords keyword tool. Spend just a few minutes running "exact phase" trial keywords related to the subject of your post. Then, favor the higher frequency search terms, when you write.
After writing a post, I keep my quick-and-dirty keyword list visible during final editing. In many cases, I have found that the descriptive phrases that I use naturally when I write are not optimal. For example, I write a lot about investment costs, and I instinctively use the descriptive phrase "low cost mutual funds" when I write. However, this is a suboptimal choice from a keyword perspective, because 10 times as many Google users will be searching for "no load mutual funds". So during final edit, I just change "low cost" to "no load" a few places in the post, and this significantly increases my potential exposure to SE traffic.