Are there any small surprises in the experience you’ve designed? “Surprise” could be a new addition or a variation on something routine, such as stating a confirmation message differently or changing an image on a familiar page. Also consider how you can get people’s attention by deviating from expected patterns set by other sites or experiences external to your site.

If people must wait for your system to return content or run a routine, create the perception that things are moving faster than they are. Use slower preloaders—we tend to count cycles, not milliseconds. Reveal content as parts are loaded rather than waiting to load everything at once. Or, offer a fun distraction: people who are mentally engaged in a task don’t notice how long it takes.

What can you give away? It could be a free account or an upgrade. Maybe a free report—or example, personal informatics are interesting. Perhaps a gift card. Make it something unexpected. And if other similar services are giving away the same thing, it’s not a gift—it’s expected.

How are people allowed to express themselves on your site? Selecting widgets, choosing content to follow or share, using emoticons, and customizing the aesthetics of a page are all ways to enable self-expression. At the simplest level, allowing comments can be a good start, but make sure these efforts are linked back to a person’s profile. Look for ways to surface and celebrate these unique customizations.

How can you add surprise and delight? Maybe it’s fun microcopy, a link to an amusing video or a compliment. Perhaps it’s an “Easter Egg” such as a coupon, virtual gift or humorous image that’s hidden within your site. Even the satisfaction of discovering a connection or solving a mental puzzle can help form a favorable and memorable impression.

While commonly used to promote purchasing behaviors, limited durations can also be used to shape day-to-day behaviors. Set limited times when certain actions can be taken. Make rewards available at specific times or have options that disappear if no action is taken within a specific period of time.