In this section I am going to offer a number of insights and tips that I have gleaned from fellow DM's and experienced myself over the years. This is by no means a comprehensive list of what is important, but perhaps all that experience will be of some use to you. Here we go:

1. Make sure the PC's are a part of the game world. As you can see from the planning and character generation sections, a lot of work needs to be put into the game world before you even begin. One of the best ways to do this is to make sure the PC's describe their families. The game world concerns of their various family members are a valuable tool to impress situations upon the PC's. When the bandits have raided your uncle's farm it's suddenly alot closer to home than if it's just another peasant. It stands to reason that the PC is likely to be either something of a "family celebrity" or something along the lines of an outcast for pursuing the adventuring career. Either way, there will be people in the game world, friends from youth, family who may have all sorts of ideas about what the PC ought to do.
2. Keep notes. Keep track of the game date. Simple things like rations running out can make a game much more interesting. Knowing where the PC's were last time lends depth, colour and credibility to the world. Take the time to simply make rough notes of where the PC's are. Make more specific notes of the various NPC's met and their general attitudes. It's best if you centralise this data when you get home after a session, but I will admit I generally am to lazy to do that too.
3. The weather. Try to make an effort to describe the weather every game day. Keeping track of the date allows you to link this to the time of year. Make the world realistic by making it harder to travel in winter and so on. The adventuring season is generally during the spring and summer, perhaps a part of autumn. Let the conditions reflect this. Have the rivers swell in spring and let nature take care of some of the danger.
4. Passers-by. Take the time to actually point out the presence or absence of others in the area where the PC's are. This is a part of giving good descriptions of the area the PC's are moving through. You are, after all, all the PC's have to interface with the world. If you don't give them good info it's very difficult to deal with what happens in the world.
5. Be Dynamic. This means that you keep a careful eye on what the players do, say and think. Allow the players to co-DM in a way, even if they don't know they're doing it. If you need a map of a place for the battle or whatever, let the players draw it. This takes a part of the workload off your shoulders, and even if it's something different than you envisaged it doesn't matter. The world is created together, making an interactive tale between the players and yourself. Allow things to change. If there's a battle on, and it suddenly turns out that most of the players had a different image in mind than you did, well, why not adjust your image to fit theirs? This allows you to utilise NPC's to their full potential making use of the terrain offered.
6. Be Dynamic II. This is an important point to lead the campaign on. Listen to what the players are saying. From time to time, you can let something happen, like for instance an assassination attempt by some exotic soul, without having any real thoughts behind it. Watch the players speculate on it and retrospectively add it to the plot. Nothing like a player who eventually finds out his theory was right all along. Also, sometimes you should listen to the speculation and do precisely the opposite. Encourage the players to speculate, because it's together that the story takes shape.
7. Don't waste time on things other than the PC's. Don't worry too much about the rules if it doesn't directly concern the PC's. It takes a bit of training, but it's much more valuable to describe a valuable cinematic battle between NPC's than it is to roll it out. Essentially, if you are in possession of the stats for both the parties involved, it's generally better to tell a story or give a good description than it is to roll it out. Even if you honestly don't know who's going to win, just flip a coin, so to speak. Just don't let the rules get the better of you. They are a tool.
8. Minimise the non-game related chatter. In order to have a good game, you need to achieve an effect known as "suspension of disbelief". To do this, you want to get people into the mindset, where they temporarily forget to remember that they are all really sitting around a table eating chips and drinking beer. You want to get them into their characters and keep them there. Especially in the beginning of each session, expansive, flowery descriptions help to do this. Also, you should take a dim view of players who consistently shatter the suspension. Thing is, everyone is there to have fun, and that's fine, but try and get them to do it within the roleplay structure. Someone who consistently destroys the cloud-castle that is a succesful roleplay session should probably be playing monopoly.

These were a few simple pointers for keeping your game on track. Hopefully they will be of some use. I have to say that I don't really know of any literature where my way of doing things is supported, but here you go, do with it what you will.