Should one say "farther" or "further"? Grammarita's rule: use "farther" if possible. Go farther, read farther, probe farther, but speak further, and investigate further. "Farther" should be for some type of distance, "further" for other situations. One of Ford vehicles' slogans is simply, "GO FURTHER." Now, can you go fur? Then how can you go further? No, you can go far; so you can go farther. Whereas "farther" is the comparative of "far," "further" is not the comparative of anything; it's just a helpful word unto itself and works well when "farther," and "far," don't make sense, as seen in a couple of examples above.
Don't use "if" if you can use "whether." "I don't know whether I can run that fast." Notice the following distinction: "Let me know if you are coming" means contact the speaker should your arrival become planned. "Let me know whether you are coming" means to inform the speaker of your plans--yea or nay! The latter is the equivalent of an R.S.V.P. (respond, if you please).
Don't use "or" if you can use "and." Example: In response to, "I'd like to buy a used car," the salesman should not say, "We have Toyotas, Nissans, or Mitsubishis." He thus seems to be saying, "Guess which of the three we have." "We have Toyotas, Nissans, and Mitsubishis" gives the customer a nice choice. Note the following, though, to avoid confusion: "What colors are your used cars?" Answer: "Red, white, or blue." The alternative, "Red, white, and blue" might make his car lot sound patriotic but quite limited!
Don't use "lesser" if you can use "less." As they say, keep it simple, Stupid. Example: "Buy one, get one free (the free item will be the one of less value)." "Lesser" still will find its place: "Choose the lesser of two evils." By the way, use "less" for non-countable items, "fewer" for countable ones: less cake, less time, even three hours less (you wouldn't say "three hours fifteen minutes fewer"), and less than two thousand dollars; but fewer pencils, fewer steps, and fewer pieces of cake.