1st. HEED THE THEFT WARNINGS AT THE TRAIL HEADS. My vehicle (99 Durango) was broken into at km47, the Botanical Beach Lot out of Port Renfrew. I know of another vehicle at one of the mid-way trail heads that was also broken into. RCMP says it's an increasing problem there.
2nd. If you're not from the Northwest, don't underestimate the rain factor... over 36 feet each year (Note: Feet, not inches!)
3rd. Bear Bags (some metal caches are available, mice love them). Vancouver Island has more bears per mile than anywhere else on the planet)
4th. Know the tides and try to walk at low tide.
The trail itself is well marked, but poorly maintained. Some minor bridges were broken or missing, steps have eroded, and trail is poorly ditched. Expect deep mud, even if not raining. Also there are numerous fallen trees, and sections of washed out trail that are very difficult, even without a pack. The section from Bear Beach north to Sombrio has about 15 hills, 3 hills in the last 2km. Camping is very limited, especially on the northern half. There is no park camping at Port Renfrew and you will be removed from the trail head if you camp there.
Saw Sea Otters, a Bear at the trail head, lots of tide pool biology, great views of the Olympics, and huge old growth rain-forest.
Out of the way (not for at least one thief) and a bargain compared to the West-Coast Trail.