Use short words

“Short words are best and the old words when short are best of all.” 

-- Winston Churchill

A style guide at The Economist has this to say:

Use them. They are often Anglo-Saxon rather than Latin in origin. They are easy to spell and easy to understand. Thus prefer about to approximately, after to following, let to permit, but to however, use to utilise, make to manufacture, plant to facility, take part to participate, set up to establish, enough to sufficient, show to demonstrate and so on. Underdeveloped countries are often better described as poor. Substantive often means real or big.

You really don't want to be this:

sesquipedalianism \ses-kwi-PEED-l-iz-uhm\, adjective:

1. Given to using long words.
2. (Of a word) containing many syllables.

It is very true that when the experiment of dictating is first tried, the luxury of the ease it gives is apt to be so great, that it tends to looseness and verbosity of style; for there is no better check on sesquipedalianism than the necessity of writing down one's sesquipedalian words for one's self.

-- Christian Examiner, Volume 72

History: 1615, from L. sesquipedalia verba "words a foot-and-a-half long," in Horace's "Ars Poetica" (97), nicely illustrating the thing he is criticizing, from sesqui- "half as much again" (see sesquicentennial) + pes "foot"

-- Dictionary.com