This is another important aspect, the ability to be neutral. Yes, in life we have favourtism, we prefer our group of friends over people who are not in the group. This can even lead to the superficial level, we prefer to talk to good looking and well presented over ugly and badly dressed people. No point denying it!
Neutrality must be enforced in your sessions, having favouritism can cause other players (who do not feel favoured) to feel jealousy towards the favoured player. This saps the enjoyment out of games. For some people it can take a lot of mental effort to treat all the players fairly, but it can be done. Favouritism can also work the other way as well. We, as humans, like to treat those that we do not like negatively such as ignoring them or inflicting cruelty. As a DM, you have the power to manipulate characters by providing experience, gold, equipment and monsters. Don't be mean to a player you dislike by causing all the monsters to attack that character, or deducting gold or experience. The other players will probably loose trust in you as a judge of situations. Loosing trust in a DM is one of the worse things that can happen in any game. No trust, then the players will keep secrets, which will fuel the distrust even more. If a player is behaving badly then take the player aside and tell the individual their behaviour isn't appropriate. Try and find the source of their behaviour, are they bored? Frustrated? Under valued? It can be a difficult thing to value each player equally without your biases coming into play, but it can be done! However, at the same time you want each player to shine at a certain point in the session, at least once!
A good quality to have in everyday life is the ability to be flexible. Being able to adapt to the different players demands can also be a difficult, but do able thing. If the rogue wants to steal from a nearby house, then let the player do that, even if it's not part of the story you wrote! It requires thinking on your toes but also requires good knowledge about D&D. You need to the ability improvise to be able to be flexible. For example, I once had a group of players who attacked a guard and I had to improvise the party being chained up in jail with all their belongings with them. I had to quickly think how the characters would be able to get out of jail, how they would get their belongings and how they would get past the guards. It was no problem, the players felt creative tonight! The wizard cast ray of frost into he rogues face (to make him look blue), the rogue then got a blanket around him and managed to successfully scare the guards away by convincing the rogue was a ghost (a good roll on a bluff check haha!).
Just how a bard can enchant everyone with his stories and how a joke can be seen as funny it's the way the stories and jokes are expressed to get this effect. Varying your tone, maybe throw in a few funny accents and gestures then you're on your way to being a good story teller! You ever listened to speeches and switched off? Bored? Most likely the speaker was very monotonic with his or her voice and had a lot to say. The evidence is clear when the person next to you has fallen asleep.
I don't mean the spell clarity that makes you immune to all mind-affecting spells but how the DM presents information. It's important to have clarity, be clear about what you want the players to do, expectations. Be clear about describing the locations of places and about what is happening. It's important not to mumble, for key information you want to communicate will most likely be lost in a sea of grumbles. A clear DM is a happy DM...Kinda...
Think about happy things in happy places. Nah...this last point is about having an upbeat and positive DM. This emotion can be infectious and from personal experience, I sometimes feel like I have to be a cheerleader to urge my group to role play and play the game! Positivity can be displayed on a vocal level, using positive language, saying nice things and being helpful to players. There is also a body language level, use open palm gestures, smile and avoid frowning. This can be applied in real life and people will find you more approachable, including your players. Having a grumpy DM will make the players feel like they are a burden and feel uncomfortable playing the game with the DM. So, be happy, mon!
There it is, my top 5 tips. Hope you enjoyed it!