1) One of the most difficult things to do with an online store is to optimise it. What you need to do is consider making each one of your product descriptions into a full page. Take a look at how Amazon set out their products, picture at the top and descriptions and specifications and other content and links below. Seems to work well for them :)
2) On-site optimisation is important but equally important is back links this tells Google that you are one of the good guys each one acts like a vote in your favour. It is best practice to get back links from more authoritative web sites this means web sites with page rank of 1 or over. The back link text also needs to contain the relevant key word for the page it is linking too. But remember the link will work best if comes from a web site that is in your line of business, but not in direct competition.
3) Instead of starting from scratch on product descriptions try to recycle your common product descriptions and make them as unique as humanly possible. Remember to use the keywords most relevant to the description of the page. Think of the shape of a Christmas tree the star being your page title and all other related keywords filtering down to create your content. Try mixing in your keywords using different variations, then read it back to yourself out loud, it should sound natural.
4) Try to cross reference related items between individual product pages when possible - accessories, similar products, products on sale. What this does is add relevant content to each page and helps you to create an internal linking system.
5) Really try to get product reviews as these can help customers decide if they should buy or not. This is also helps you create fresh content; a good way to get feedback from customers is to offer a good discount on their next purchase. It is also good to get independent reviews from external web sites as your own web site reviews could be seen as less accurate, try to get a healthy balance between the two.
6) You probably engage on social media sites like facebook and twitter (if you don’t you should look into it) Good practice is to look for groups and discussions with something related to your field of business. Do not go in with sales pitches; get involved in conversation get to know people and the time to describe your items or business will naturally arise. Running competitions are a good way to get people talking about your product (people tend not to do a lot for nothing - make the prize decent enough and it should attract attention - traffic and leads could potentially generate enough to cover the cost of the prize)
7) Add quality content to your web site by helping your customers come to a decision, this might be in the way of articles on - choosing your first ___ or how to use ___ properly, check lists for expectant mothers for example (build one so they can print it off, plaster it with your contact details, web site address. You could even go as far as having a discount code associated with using the check list - could entice them back.