The other thing to do is to avoid "trading up". So many people buy more house and more house and more house as they grow older and their income increases -- but they'll never get it paid off. We're in our second house, and we've never had a mortgage on it. Yes, most of our friends have bigger, nicer, newer houses, but ours is comfortable and PAID FOR. Now that we're mid-40s, many of our friends are concerned about their kids' college educations and their own retirement . . . but we're not, and having chosen to stay in a modest house is one of the biggest reasons that's true. We've never been particularly high wage earners, but we've done a great deal with what we have.
I have a number of friends who've realize in their mid-40s that they are closer to retirement than to the beginning of their careers - generally shortly AFTER they take out a 30 year mortgage on a big house and their oldest starts middle school and they wake up to "but I have to save for retirement and pay for college." (Honestly, some of my friends are slackers who wake up at 40 to "I'm close to retirement and I haven't STARTED anything like a career, or a family.")
My advice to anyone starting out - live beneath your means. Make yourself comfortable at a reasonable standard of living. Think and plan ahead. You'll be 40 in what will seem like a few weeks - and I'm sure in a mere few weeks (I'm 45, my kids are eleven and twelve), the kids will be going to college, and a few weeks later, I'll be 65. Make hay while the sun shines and save it for a rainy day. Don't do this at the expense of being comfortable - no one should bank a million dollars and live off ramen noodles and wear holey underwear - but do this before you fall for those beautiful granite countertops. You don't have nearly as much time as you think you do, either to live for today or plan for tomorrow.