vacuum -|- There's no trick, instead of the -ume that creates the same sound in volume, there are 2 U's in between the -c and the -m. 

valleys -|- Because this word ends in an –ey, you cannot drop the –y, so you simply add an –s to make it plural. 

valuable -|- It would be valuable to remember there's no e.  

vilify -|- You may be tempted to keep the double l from villain to spell vilify, don't; one is just enough.  

vicious -|- When spelling this word remember the –cious creates the "sh" sound.