Born in England, he played for the Sierra Leone national team during his career and currently serves as its head coach.

[1] Keister started his career at Sierra Leone side Tigres in 1992 before moving to England in 1993.

Since living in England he has played for Walsall, Chester City, Shrewsbury Town, Stevenage Borough, Margate and Dover Athletic where he was captain before returning to previous club Margate on a free transfer in September 2009.

[2] Whilst playing for non-league club Margate he gained two international caps for Sierra Leone.

Following a spell at FC Johansen, he was appointed as manager of the Sierra Leone national team in 2017.