By ship
If you are starting from Vancouver, catch the ferry from Horseshoe Bay or Tsawwassen to Nanaimo on BC Ferries, and drive the rest of the way.
In the summer you can catch the M.V. Frances Barkley (http://www.ladyrosemarine.com/) from Port Alberni to Ucluelet 37km south from Tofino, 4.5 hours, $30 one-way.
By car
Tofino is accessible via Highway 4. The road, best driven during the day, is very twisty and narrow particularly west of Port Alberni but offers great views of lakes and mountains on the west coast. Coming from Victoria, take Highway #1/#19 north 160km to the Highway 4 turnoff west to Port Alberni.
By bus
Tofino Bus Island Express (http://www.tofinobus.com/) runs service in conjunction with Greyhound on Vancouver Island. Routes make stops in Nanaimo and Victoria among others between Nanaimo and Tofino.