Formatting
Most Flashed sites I'm asked to critique can improve their formatting.

• Sites have scroll bars on the side.
  Take a look at Colin Moock's tutorials to fit the Flash movie perfectly inside the browser window.
• The size of the movie is specified to a certain size.
  Specifying a pixel size (rather than a percentage) makes your site look different in different resolutions. Some users will have to scroll down to see it, some will even have to scroll SIDEWAYS! If you're going to specify the size of your movie (instead of going 100%), make sure it's compatible with the most number of browsers (no wider than 700 pixels).

Color Theme
Before you start getting REALLY into your design, it's best to pick your favorite 2 or 3 colors as a color scheme and stick to it.  Too many sites use black backgrounds with a sentence in purple, then blue, then yellow, then a rainbow, then.... ugh!

Fonts
Flash will use just about ANY FONT IN THE WORLD.  For this reason, avoid using standard, every day fonts like Arial and Times New Roman.
Want some cool fonts? Click Here!

Sound

• Make sure if your site has music, it either fades out or has an "Off" feature!
• Try and avoid using the small collection of sounds that come with Flash.
  Click here for more information.

Speed
I recommend a frame rate of at LEAST 24 fps.  This makes animation a lot smoother than the default 12 fps.  Contrary to popular belief, using a higher frame rate does NOT crash computers or bog down slower computers.  If anything, it makes animation faster.

Animation speed
If the animation of your movies seem slow, file size actually has nothing to do with it! Complex symbols, such as a word with gradients, masks, numerous layers and lines will move across the screen slower than simpler symbols. Objects animate faster when they take up a smaller portion of the screen.

Optimizing

"Mr. Dude, I have a Flashed site.  How did you optimize yours so good?
My file sizes are HUGE!"
Here are some tips:

• Optimize every single object in the Flash Library (Ctrl+L). This is done by:
  • Removing unused lines and fills in the object.
  • Using the "smooth", "straighten", or "optimize" commands.
  • Setting specific compression levels for all bitmap images.*
• Avoid bitmaps unless absolutely necessary.
• Play with the export settings of each sound in your movie (see Sounds)

*Consult the manual for more information.

Preloaders

"Mr. Dude, how is it that your site's current teaser doesn't need a preloader?"
I try and avoid preloaders at all costs! If I don't want to sit and watch a "Loading" screen when I access it online, why should I make others suffer? Don't be lazy when creating a Flash movie! Think it out first, and follow these tips:

1. Use mostly vector-based graphics in the beginning (no photos).
2. Use a short music clip for the opening loop.
3. Space all other graphics and music clips far apart from each other in the movie, at least far apart enough that each piece will be loaded before it shows/plays.

Basically, my site's entire opening movie is a preloader, as there are no large chunks of data that are on the timeline before they're loaded. In other words, a music clip or graphic will show just after it's been loaded.

Coordination

"Mr. Dude, how can I synchronize Flash's sound and music to the action on the screen?"
No Flash movie will display at the exact same speed on any two machines, or even on the same machine at different instances. What may appear to be synchronized on your computer may lag noticeably on another machine.

Your only option is to use the "stream" event, like I did with The Perfect Storm. However, Flash will drop frames in the animation to keep up with the sound, which may result in visual skipping.

The solution: be strategic when designing your Flash movies.