Hi Chris,
If your product is in a market that is saturated, high volume, and highly competitive (like iPods or hiking boots) then stick with Egol's advice.
But from your profile it appears you sell specialty table legs, and I think that may be in a different realm of Adwords where the volume and competition are both low. The products my two stores sell are specialty items that are low volume and low competition, so I can share my experience.
The executive summary is "Start generic and start cheap". Doing that will give you an education focused on your niche at a reasonable cost.
My specialty items do not have a high search volume, so starting with broad keywords allowed Adwords to give me data on the full range of keyword searches it was actually displaying for. Depending on the search volume, it can take a week or three for Adwords to create a good list of actual keyword searches. As this list develops, use negative keywords to prune out phrases that are just wrong. Also start to add phrase and exact match for the phrases that appear often.
And I mentioned "start cheap" because Adwords has this weird habit of over-valuing itself. If I start with a bid of $0.15 it will immediately tell me that I need to bid $1.80 to be on the first page. If I ignore that expensive suggestion, I appear anyways. It may take a couple of days, but I will appear on page 1 or 2. Then I can start upping my bid a nickel at a time until I appear in the upper slots.
So budget $100 to do live research on Adwords, and consider it a market research expense. During that time, also go to the library and use their public computer to make a test purchase after clicking one of your ads - to be sure the tracking is correct. Also never delete a campaign, instead pause it so that the old data is always there to refer back to.
So much more could be said, but I need to go eat breakfast. You are welcome to contact me through one of my stores. Just google my name without the "ory". Good luck!