This all sounds like good advice from good DMs. I have been playing since I was 6 and I am 35 now...
and I have seen some great, good and terrible DMs. Creating paranoia in players is priceless. Guiding the players to the right end of an adventure is your goal but it is also your goal to make it hard on them and to test their abilities and their creativeness. If its not a challenge, they will grow very bored very fast.
I have seen first time players out think seasoned veterans by having a fresh outlook. Help new players out and if you have a group of old players and a new one...make the new person feel as if they are important and not just a tag along. I usually aim a lot of the plot and dialog their way and nudge things toward their character to solve. Good players should help in this, too.
More advice...beware the players when they huddle up in a corner before a big battle. They can come up with some wonderful tactics! The DM should also play monsters with the intelligence they have and not just an mindless obstacle. I one whipped a level 12 party with some kobolds who were just 4 hp but nasty cunning.