First off ..... this "list" assumes you have your domain name, your website, your product, and your people (if you have a staff). If you still need a website there's resources listed here at Small Business Resources Cafe that will provide you a quality high performance business website.
Now, assuming you don't have a business plan .... this is what I suggest. It is simple ... to make you think ... and fill in the "effort" blanks. This also isn't meant to be "THE" list. I'm sure others may have suggestions too. If so, by all means share them as comments.
1. Develop a business plan. This will be your roadmap for what, how, when, where, etc. Plus .... if/when requesting funding from anyone they will ask to see your business plan anyway.
2. Completing #1 will help you define who your target market is. Once you define that .... determine the best way to reach that market. Online (where, how), and/or offline (where,how).
3. Develop your marketing strategy based on #2 (in keeping with your process, goals, resources, budget, etc. defined in #1).
Since your focus is online marketing (per the boundries of this article) .... develop and execute your online marketing strategy to include SEO (search engine optimization), social media marketing (branding), building a customer list (attracting target market), and email/follow-up marketing (with your list).
For offline .... what opportunities reach your target market? Define those and pursue them. For example ... trade shows, local special events (e.g. fairs, festivals, open houses, etc.), local media.
4. Develop partnerships with local businessses where synergy exists between your products and theirs, and your target market and theirs. For example pet health products in a Vets office or pet store. Offer a win-win relationship of some kind (profit sharing or customer referals). These partnerships can be with brick and mortar businesses or online businesses.
5. Develop and implement metrics to enable constant evaluation of results. "When we do this .... this happens." Make business decisions based on data .... not the seat of your pants. These are called by some "business analytics".
I hope that helps some. Pretty genric but will hopefully give you some ideas.
Now don't just sit there .... get going!