Answer by taking a quote from the following article:

James Hudson Taylor (Chinese: Dai De Sheng ; 21 May 1832 - 3 June 1905) was a British Protestant Christian missionary to China and founder of the China Inland Mission (CIM, now OMF International). Taylor spent 51 years in China. The society that he began was responsible for bringing over 800 missionaries to the country who began 125 schools and directly resulted in 18,000 Christian conversions, as well as the establishment of more than 300 stations of work with more than 500 local helpers in all eighteen provinces.

Taylor was born on 21 May 1832 the son of a chemist (pharmacist) and Methodist lay preacher James Taylor and his wife, Amelia (Hudson), but as a young man he ran away from the Christian beliefs of his parents. At 17, after reading an evangelistic tract pamphlet entitled "Poor Richard", he professed faith in Christ, and in December 1849, he committed himself to going to China as a missionary. At this time he came into contact with Edward Cronin of Kensington--one of the members of the first missionary party of the Plymouth Brethren to Baghdad. It is believed that Taylor learned his faith mission principles from his contact with the Brethren. Taylor was able to borrow a copy of China: Its State and Prospects by Walter Henry Medhurst, which he quickly read. About this time, he began studying the languages of Mandarin, Greek, Hebrew, and Latin.  In 1851, he moved to a poor neighborhood in Kingston upon Hull to be a medical assistant with Robert Hardey, and began preparing himself for a life of faith and service, devoting himself to the poor and exercising faith that God would provide for his needs. He practised distributing gospel tracts and open-air preaching among the poor. He was baptized by Andrew John Jukes of the Plymouth Brethren in the Hull Brethren Assembly in 1852, and convinced his sister Amelia to also take adult baptism.  In 1852 he began studying medicine at the Royal London Hospital in Whitechapel, London, as preparation for working in China. The great interest awakened in England about China through the civil war, which was then erroneously supposed to be a mass movement toward Christianity, together with the glowing but exaggerated reports made by Karl Gutzlaff concerning China's accessibility, led to the founding of the Chinese Evangelisation Society, to the service of which Hudson Taylor offered himself as their first missionary.

What was his first job?
In 1851, he moved to a poor neighborhood in Kingston upon Hull to be a medical assistant with Robert Hardey,