To overcome this challenge then you have to do the following,
1.Get information regarding all the professional certificates that relates to the job you want to do.
2.Its only the oil and gas sector that recruit directly from Nigeria but other sectors looks into the local market here,so you must get a work visa to come over here first after you must have gotten all the related certificates that are going to be useful for your job search.
3.Getting job here when you are qualify is great,although sometimes its may be tough too just like anywhere in the world.
If you needs more information,then dont hesitate to ask.