One option would be to try to find work through or at your embassy. Project management, financial control and general management positions are further fields of interest. Be prepared to share knowledge with local Ghanaians, it is highly expected. You should do it even though it can lead to a replacement by a local worker in the medium term.
In general, people relocating to Ghana already have a job before entering the country, usually with an internationally operating company. It isn't generally recommended for expats to enter Ghana and search since it is almost impossible to find a job, especially with the existing quotas. The number of expats that are allowed to work in a company depends on the money a company has invested. Moreover they may only be hired if the position cannot be filled by a Ghanaian.
If you do not have a job now, the best place to search is probably the Internet. The most suitable homepages for that purpose are either Ghana specific ones like Ghana Web or Joblist Ghana or African wide homepages such as Careers in Africaor Find a Job in Africa. Since Ghana isn’t a popular destination yet, you may even have problems finding vacant positions on the most popular global job portals, so it’s best to try the specific ones.
If you look for an alternative to the Internet and you are already in Ghana you can consult newspapers like the Accra Daily Mail, the Ghanaian Chronicle or the Ghana Review International.
When searching online for jobs you should be careful. Many representations of western countries explicitly warn against scams from African countries. Make sure the company exists and has a real homepage. Never ever transfer money to them, regardless of the reason they give you. E-mails, sent to you without an obvious reason are usually fake.
Your job application should contain everything you would include in Western countries: A cover letter, your CV and sometimes an application form. International companies tend to do the first interview via telephone or Skype or they will invite you to an office in your country if possible. Of course there is the possibility that you have to travel to Ghana for an interview. Either you have to organise the flight yourself or they will provide you with tickets. Do not pay them to organise your trip (a well established company wouldn’t ask you to do this) as you will most likely never hear from them again.