As a not-so-young-un, I learned what was explained in this kind piece long ago, and now Make-It-My-Business to Always-Carry my hand-written grocery list with me and try to only purchase items from my list. On another note, that(your) lead image is magnificent, both for it’s imagery as well as for it’s obvious subject.
Yes, definitely these are the painless steps to speed up Mac but performing manually doesn't yield perfect results. Apart from emptying trash and separate trash of iTunes and iPhotos also eat up lot more unnecessary space. Downloads area also occupy useless space. Emptying it also speed up Mac.