A taxi or Hired car) is recommended for getting around on the island, especially for first time visitors. Get an island map at the Montserrat National Trust. Note that street names and house numbers are not the norm here, however most places of interest are well known and people will be happy to direct you.
If visiting Woodlands, Olveston and Old Town you may need to get detailed directions. A detailed map from Tradewinds Real Estate is useful. Note that the exclusion zone in the volcanic south is strictly out of bounds, and this should be respected.