I just finished critiquing the first two pages of a young writer friend's thriller. That exercise reminded me of all the things to remember about opening scenes.
The first page of your novel is the most important. No, I'm not exaggerating. That page will be the one that agents, publishers and readers look at to decide whether or not to continue reading. That page needs to do three things: (1) offer a hook to make the reader want to read on; (2) provide a sense of your writer's voice; and (3) begin to offer clues to the world you have created.
Do start on a moment of action with SOMETHING happening. Set the pace.
If you start with dialogue, make it interesting dialogue (I began Dying to Do It with the line, "Put the gun down, Wayne.")
Use action words.
Use sensory words: Don't limit yourself to describing what is seen. Describe smells, tastes, sounds and touch as well.
Limit the number of characters you introduce in the first chapter. Don't overwhelm the reader.
Do not start with a long, lyrical description of a place or the weather.
Avoid "ing" words or forms of the word "to be" (was, were, been, have been). Say "ran" instead of "was running."
Avoid a lot of backstory (what happened before the story starts).
Avoid extended narrative.
Use adverbs ("ly" words) sparingly.
A good exercise for writers is to read the openings of some of your favorite books. Decide what it was about those openings that engaged you.