I love scrapbooking! I've done a dozen or so over the last 10 years. I'll share my own tips for you, but it's really about your personal style.
I think the biggest mistake people make is overcrowding the pages with stuff. The pictures should be the main focal point with a few small accents according to your theme. That's pretty subjective, though, it all depends on what you like.
Journalling is really important. Leave room to write the memories and stories. I'm so grateful that I wrote so much down when my children were little. Now I go back and think, "Oh, I'd forgotten they used to do that!"