The absolute, most positively best way to acclimate to android and smartphones is to...drumroll...PLAY WITH IT!
That's that, you need to decide what you like!
As for bloatware like the sprint apps, you have to root the phone to be able to remove that. If you go to the root subthread, you can learn all about rooting, so take that out. One word of caution, do NOT upgrade to 2.2 if you want to root, wait it out until you learn about the phone.
Browse these forums, check out article and posts, see what people like and say. There are alternative launchers to make your phone look spiffy, check out LauncherPro or ADW Launcher. There are messaging apps to shine up your txting life, check out Handcent SMS and Chomp. There are interesting games, check out Jewels and Abduction. So, so, so much you can do.
I recommend a couple things:
1. Don't download an app killed like ATK. Read the post above about task killers and android - you don't need em.
2. Download Astro File Manager, so you can explore your SD card - there is no stock way to do so, so you have to get a market app.
3. Enjoy Facebook and the contact sync, it is simply fantastic.
4. Touch everything, open everything, play with everything. You will learn at your own pace and through experience, so just enjoy your piece of equipment to its fullest potential.
5. Let me know if I can be of any further assistance.