Be fore you start dyeing stuff go get a box of Mr Clean Magic Erasers & try scrubbing it with that...It does a pretty amazing job...If it doesn't get things clean enough to satisfy you at least it's a good preperation step for dyeing...The problems with dyeing are 1)loss of grain pattern 2)it sometimes peels if the surface wasn't clean enough or the dye was of questionable quality 3)once you've dyed the part you really can't completely remove it....

If you decide to dye SEM & Mar-Hyde both give good results but over time it will fade & then you'll want to do another lap with the dye so refer back to "The problems with dyeing"...