which strategy should i use for sem e.g free registration in directories, ads, forum postings, social marketing, blogs etc
Yeah freee registration in web directories would be ok, ads too. The SEM strategy could be diferent in case of a link directory and a online shop. Can you PM me your site and I can give you more precisely tips.
Put your site in the signature and comment on blogs with dofollow. Submit your site to web directories. It won't give you a lot of traffic but there will be a constant number of visitators.
It would be best if you have a blog, either separate or within your website. Google favours sites that provide information. Article marketing is also another good SEM tactic. Submit unique articles to different article directories like ezinearticles.com, buzzle.com and articlesbase.com. Never, ever submit duplicate content to article directories or even articles that are already on your site. This way, you will never be in danger of being penalised by Google, if they will come around to doing that. Continue forum posting. As long as you post relevant comments and topics, you will be fine. Once you have posted the required number of posts, you will already be able to place signature with a link back to your site. Do blog commenting also. This is good in creating relationships with fellow bloggers who are more than willing to help you out as you go along. Most of them also use of a commenting system that allows you to link back to your site. Hope what I gave you will be of help. Good luck!