The HIP system is something we all know about, on a different level, but it bears repeating because in my opinion, writing a good scene is hard. We know what we must strive for, but nailing it isn't so easy. It takes practice.
Again, all credit for this goes to James Scott Bell. If you want more, you'll have to pick up Plot and Structure.
What is HIP? An acronym (I think Bell loves acronyms, he has quite a few of them) of what you need in any scene: hook, intensity and prompt.
H for Hook. Start with something that raises questions. You need to grab your reader right off the bat and make him want to read on. All those tips for first sentences in a novel? Apply them to first sentences in a scene. Most of the time, location isn't your best bet. Be daring. Tease your readers before you describe the setting.
I for Intensity. Scenes need to be intense, or your reader will get bored. Pack them with tension and increase the intensity as the novel advances. This doesn't mean action; emotional turmoil can be just as intense. What you need is a simple thing: conflict.
There should be conflict even in scenes between friends or allies. Play with their opposing agendas. Pit their opposing personalities against one-another. Make sure there are sparks flying. Turn every dialogue into a sparring contest. Make your scenes so tense the actual page is shaking. Or, well, maybe not, but you get the point.
P for Prompt. Don't end with something boring. Give your readers a reason to keep going, even if it's 4 am and they work early. Prompts can be impeding danger, mysterious dialogue lines, important announcement or vows... anything major, really. Just don't end with "Good-bye" or "He left the office." End with something interesting.
Or, as Hitchcock used to say... "Cut out the dull parts."