Having learned about Google's keywords selector in the last step, you can use this to choose a relevant title for your Instructable. Google weights the first and second word of your title as heavily important in deciding whether it's relevant to a user's search and so your title should match one of the high volume searches if possible, so long as it doesn't dilute its relevance.
Also beneficial is repeating your chosen keywords from your title several times throughout your Instructable. Be careful not to overdo this though, doing so is known as keyword stuffing which may have a negative effect on your search ranking and the writing style of your Instructable.
When referencing other's works or another source of information, always write good anchor text. Google tries to reward pages that are easy for users to use/understand and one of the ways they do this is is with outgoing links. You'd get more brownie points for the first sentance than the second:
1) For a good basic introduction to SEO basics see Google's search engine optimization basics guide
2) For a good basic introduction to SEO basics, click here
Doing so makes it easier for users to navigate and easier for Google to understand what you're linking to.
These are much less heavily weighted by Google than other metrics, keywords are more beneficial for Instructables' internal search so don't worry about these too much for external search. The keywords field in your Instructable should have the important words from your title as well as common alternatives or relevant similar words that would otherwise dilute your title. Some examples of these may be if you were making Canida's Fruit Tart
then you may consider the following keywords as relevant and why, her Instructable is a good example of keyword use:
peach, nectarine, berries, jam: because these are the main ingredients. More to the point, they're ingredients people would be searching for. You wouldn't want flour, eggs, vanilla extract in there, they're not appropriate as no one would search for a flour tart.
pie, flan: other words for a tart that people might be searching for.
recipe, easy, quick, vegetarian: If when looking at Google keywords selector there are several high volume searches, you may choose to cater to one but put the extra terms in your keywords. "Fruit Tart", "Fruit Tart Recipe", "Easy Fruit Tart", "Quick Fruit Tart" may all have high volumes of searches and so adding the extra words into your keywords list or using them once or twice in the description or throughout your Instructable will help get traffic from those searches too.
Keywords to avoid because they're unnecessary are words like of, and, a, as.