1. Move to Ottawa, if at all possible.
2. Understand that, although Parliament Hill looked vast and peaceful when you drove past it last week, there is absolutely zero possibility of your packing a picnic lunch and lazing lackadaisically on the grass while various entertainers, of whom you have an unobstructed view, perform quietly in the background.
3. Although you will likely have more fun if you bring a child, it will be in the "look how cute my kid is as she runs around pointing at all the flags and yelling Happy Birthday Canada!" sense, as opposed to the "Hey it's a holiday, let's get drunk and party with a bunch of strangers" sense. It's just a different kind of fun.
4. Wear red and white. Or don't. It really doesn't matter.
5. If at all possible, arrive at Parliament Hill early, before anything really starts to happen, then leave before the really exciting stuff happens (i.e. visiting Royals, Snowbirds air show, famous musicians, etc. etc.) It's actually more fun to muse about what's everyone is shouting about two blocks over while enjoying a coffee or some lunch on a quiet patio. Less chance of losing a child or an arm in the crush of rabid Will&Kate-o-philes that way.
6. It's probably not the best idea to arrange to meet up with someone, particularly someone you haven't seen in 12 years, by hoping to just randomly run into them because you're going to roughly the same place at roughly the same time. Parliament Hill. Canada Day. As plans go, it just not very realistic.
7. Above all, remember the words of Don Cherry. No, not those. That's rude. I was thinking of "Keep your head up and your stick on the ice." It's Canada Day, after all, not Run-around-like-an-idiot-trying-to-prove-that-you're-Canadian-and-only-end-up-embarrassing-the-rest-of-us Day. It's a day to chill out and enjoy a little time with the people we love. And if you're doing that, you're doing Canada Day proud. Now take off the flag and put your pants back on.
I'm in front of Parliament Hill. Oh, you too? Hmm...I don't see you.
Look for someone wearing red and white.