Welcome to the world of EVO! I'm a newb myself having just received my phone on Tuesday. But, I've been reviewing these forums for over a month to help prepare myself.
Here's what I found helped me get off to a fast start:
1) Definitely go to
AppBrain - the best Android apps and games on the Android market, set up an account and browse through the market place and select which apps appeal to you or meet your specific needs. Everyone is different but there are some common utilities that people use for things like battery usage, file management, security, optimization, etc. Here's the link to my list (which appbrain lets people share with others).
Appbrain is also an app you need to install ( Market>Search for Appbrain > Install) which then 'syncs' all your choices from the website to your phone. The website is a great tool to allow you to search for, view reviews, ratings, etc. for all available apps, then 'add to your phone' using the Appbrain app on your phone.
rockmetal's Apps on the phone
2) Go through the Tips and Tricks > Battery thread that explains some of the services you should deactivate to get better battery life. If you don't make some adjustments you'll see your phone go dead rather quickly. Basically, after 'normal' use, you should easily get a full day out of your phone assuming you charge it every night. Don't expect days of un-ending use without charging. This is a powerful smart phone that when used constantly for surfing, game playing, etc. will drain its power source like any other multi-media device. If you simply talk on it then you're good for hours. Yesterday was my first real all-day test after making my tweaks. I had 17+ hours of active time with 35% battery left and spent a good chunk of that time showing people how it worked, surfing, showing YouTube videos, etc.
3) Get in the habit of using the power switches to turn certain 'radios' off when not needed. This is a huge power saving habit to get into. The radios are for GPS, Bluetooth, 4G and wifi. Generally I keep only wifi on since I work from my home. It uses very little power compared to the 3G/4G service if you're just doing email and web surfing. I turn on Bluetooth when i'm on long winded phone calls. (If you don't use a Bluetooth then why have it on?). And, when I need GPS I simply turn it on. All this takes literally seconds to activate/deactivate so it's no big deal having them off. But a big deal if you're conserving power.
4) Pay close attention to the settings for synchronizing your various data programs/apps. Things like Facebook, Twitter, Gmail, etc. by default are set to sync like every 1-5 minutes which is fine if that's your life. But be prepared for a HUGE tax on your battery. You can set those to sync once per day and easily go and manually update them when you want to see the new posts.
5) One of the harder things to get used to is the program specific menus. Almost every 'app' has their own menu. So, when you open an app if you hit the Menu button at the bottom of the phone you'll see a menu slide up with your various options. Also, in many cases, that menu contains a Settings selection where you would make changes to how that specific app works (like how often it may sync data, etc.).
6) Task killers - this is a hot topic in here and there's the question of IF they work or IF they are needed. I have one (Advanced Task Killer) and it works perfectly on my phone without any incidents. I can't say for sure IF it has helped my battery life but I can assure you it hasn't hurt it. The premise is that it 'kills' apps automatically that may be running in the background whether you know they are or not. Some of these background running programs could, in fact, be draining your battery. So, investigate these app killers (ATK is the most popular) and, if your battery is not giving you all you need, try one. Can't hurt. Like I said, all I want from my phone is a full day of use under 'normal' conditions (a few calls, some surfing, a few texts, few emails, etc.) and charge it every night (as I have since I started using cell phones). Right now I get that easily.
7) Don't use active wallpapers. Even if this is not a huge power drainer it IS a power drainer. Also, I have my brightness set at 25% and it's fine. The 100% setting looks brilliant and stunning but is not really necessary for just everyday use on a personal level. There's a 'brightness' widget/app you can download from the Market that makes changing the level a snap.
There's much more but this was the best 'kick start' for me and helped me avoid many of the frustrations I see listed in the forums. Plus, my phone is one of the newer builds which apparently fixed some of the discrepancies found in the initial distributions.