Go in there with a positive attitude.  The 'success' of a trip on many different drugs weighs heavily on how stable you are when you use them.
Try to make a simple plan to do something interesting, like taking a hike.  I say simple because a complicated plan may seem overwhelming when you're tripping.  I say interesting, because looking at a piece of wood can seem like the greatest thing in the world when you're high.  If wood can do that, just realize how amazing a neat patch of woods, a waterfall, a cliff, or an awesome view will be.
Smoke weed as well.  Since toking is a stimulating event, it will turn into an awesome activity while you're tripping.  Same thing with music, make a sick playlist for the experience.