Event Marketing Suggestions Requested

I represent an agency that facilitates educational family and school-related seminars, conferences, and webinars. Because of budgetary and health concerns, we recently decided to focus most of our attention on the delivery of live interactive webinars. However, marketing has been a real issue. We have been experimenting with mainly free online marketing sources to advertise our webinars with limited to no success. We have been finding it very difficult getting people to sign up for our paid and free webinars. For our paid webinars, we decided to keep our fee low in hopes of attracting people to our webinars. We also offer a free gift to those that attend a webinar. We have used the following free tools to promote our webinars:

1) Postings on free webinar sites.
2) Free online press releases.
3) Free event calendar postings on both media as well as family-oriented websites.
4) Media press release emailings.
5) Newletter emailings to our subscribers.
6) Postings on major social networking sites that we currently have a business page with such as Facebook and Twitter.

We've also tried some paid advertising services:

1) Facebook ads
2) Google adwords
3) I also once placed an ad on a parenting website. They listed my ad on their website's yellow pages or resource section located fairly deep within their site.
4) We also once hired an SEO agency to optimize our website. They charged us $1,000.00 a month for their services and we received little to no results. We subsequently discontinued our relationship with them.

All of the above marketing techniques basically have not been effective in getting people to register for our webinars. Because the majority of our advertising has been free, I tend to believe that we simply are not advertising these webinars correctly.

I have read several articles that state that advertising on social networks are very effective in drawing people to webinars. However, my knowledge of social networking sites is limited. Short of listing the webinars on our business page of the network, I'm not sure how else I can attract people to our webinars using social networking sites. We have a business page on Facebook and Twitter. Since these pages were put up relatively recently, we have very few followers.

Our budget is limited and I know that there are vast advertising opportunities on the Internet.

1) Does anyone have any suggestions of other paid advertising opportunities that I should consider that might be effective in drawing people to our webinars?
2) Should I consider hiring an event promoter or marketer that could help point us in the right direction regarding online advertising? If so, does anyone have any recommendations of reputable event marketing agencies or independent contractors that I should consider hiring?
3) Is there any other marketing opportunity that I haven't mentioned that I should consider?