Your keywords should reflect what you imagine someone might type as a query when searching to find your site. Instead use words that describe your product, company, and field. Separate your keywords with commas and consider possible pluralizations and potential misspellings. Once you show up in the search engines, you might want to fine-tune or change your key words for better rankings. With thousands of new websites being submitted everyday, competition for high rankings is becoming more difficult.
Monthly submissions is recommended for better exposure and higher search engine rankings.