In order to practice as an Engineer in Nigeria whether you possess a Nigerian certificate or foreign certificate, you must have passed both the Nigerian Society of Engineers (NSE) and Council for Regulation of Engineering in Nigeria professional exams and other requirements involved. Check their websites for more information www.nse.org.ng ; www.coren.gov.ng
Persons educated or trained in foreign countries can only practice Law in Nigeria after being trained at the Nigerian Law School. After passing the 2 main courses which are Bar Part I & II, the individual will be issued a certificate by the Council of Legal Education and then 'Called to Bar' by the Body of Benchers in accordance with the Legal Practitioners Act after which an enrollment as a Legal Practitioner at the Supreme Court of Nigeria will take place. Check the website for more information www.nigerianlawschool.edu.ng
There is no specific or compulsory step for a foreign trained accountant to practice in Nigeria. However, there are several professional exams like CAIAN, ACCA, ICAN, etc. in this field. As a potential worker, you are advised to write at least one of these exams as an added advantage to give you an edge over others.