While rated "advanced" Galbraith does have some trails for everyone. There are some very massochistic routes and some gentle routes. But for the most part, if you don't have skills, don't bother. There's a good climb to get up to the main network of trails and then an absolute ton to choose from. All trails are wet, twisty and technical. You'll find rots, roots and drops to work your skills.
How to get there:
From Bellingham take I-5 to Samish Way exit. Follow Samish way North to Galbraith Lane. You can either park to the left across from Galbraith Lane or you can turn onto Galbraith Lane and park on the left at the roads end. Follow fire roads up looking for trails going into woods that connect to a network of trails.