Tabletop RPG have been around long enough now that there are many good articles on the internet - don't restrict yourself to those on D&D though.

The art of a good GM (short for Game Master - the term used for a DM in pretty much every other game) is in story-telling, the sort of story-telling that draws the players in.

As for style - it varies by group - my preference (and that of groups I play with) is for in-character role-play at the table, adopting accents or speech patterns, as well as body language (gesturing with hands) when conversing. We have a tendency to want the story and the game to play out like a great movie, with the characters as the stars of that movie.

I've also played D&D with people who treated it more like a board game and there was zero roleplay, but it worked well and was fun.

So honestly? Speak to your group - be open and discuss how you all prefer the game to work. :)

I find the art of keeping the players engaged involves:

• Find out what the PLAYERS enjoy about the game. Some love rolling dice in combat, others love to roleplay their character in conversation, yet others love planning and tactics. It can be difficult to appeal to all players at the same time, so it can be better at time to 
• Help them build CHARACTERS with goals, aspirations, flaws and desires. Even long-time players can fall into the trap of making characters without flaws & vulnerabilities, but these are often what really make the story matter. Say the party Rogue nearly died in a fire when young, failing to rescue their family, but surviving themself. Now put them in a dramatic situation where the party are trying to stop some bad guy and the building catches fire, with an npc the party have come to like trapped - does the rogue go help the npc and save them, or go after the bad guy as planned? If they don't rescue the npc - what will the npc's young daughter have to say after? It can feel mean, but many of the best stories place the heroes through adversity.
• Never LET them win, but give them the opportunity and the tools to do so. There have to be consequences for actions and failure. The players must feel that it's possible for them to lose, otherwise winning doesn't feel a real victory.
• Advancement - players love to feel that their character is progressing, whether that's getting more powerful and higher level, or achieving goals. With loot / magical items - there's a fine balance. If the party get magic swords every session, then they form no attachment to them. Consider instead that the party fighter is able to retrieve from a dungeon, a longsword that glows with a bluish light when drawn. It has ancient elven runes drawn down the blade and always feels cold to the touch. This adds a bit more mystery to the weapon, other than just "You found a +1 sword"