There are number of SEO companies/consultants in Malaysia. Below are some factors for consideration when choosing an SEO company:
How long has the SEO company/consultant been established ?
How is the track record like? How many sites have been successfully listed into top positions?
Are those top rankings sustainable? For how long are they there - more than 1 year ?
Are the keywords used common? E.g. a company dealing with furniture should use keywords as common as possible – furniture supplier or furniture manufacturer; and not overly specific such as furniture shop Klang.
Are website listed under normal listing or "Sponsor Link" ?
Are you given a money back guarantee if your website is not listed in top position in search engines ?
Is the SEO company/consultant using a SPAM method to spam your website to get higher rankings?
(Caution: There are few irresponsible SEO consultants in Malaysia who are)