I was motivated to do this after a guy in my country hosted a game, everyone except him had 1 red bar, when I asked what his connection type and speed he had, he had no idea.
So if you aren't a technical person here's some things you can do. It's something to seriously consider with Crysis 2 having such bad lag issues.
Know your connection:
If unsure of what type of internet you're on, check with your ISP, or ask your parents if the situation applies.
All the tweaks in the world won't help you if your on a 256/128kbps internet connection.
I'd recommend at least a 1.5mbps with 512kb upstream Broadband connection. This is at the bare minimum despite what Microsoft says.
Test your speed
http://www.speedtest.net
This is one of many popular sites that will give you a good idea of your upload and download speed, just click begin test, sit back wait for it to run and it'll tell you your upload and download speeds.
It can provide extra information like comparing how other ISP's rate as well as average speeds other users with your ISP get. It can be also good to teach you how "PING's" work in relation to server distance.
Read reviews of your ISP related to gaming:
Google your ISP's name with the words "review" and "gaming" thrown in. A lot of things can effect your internet and just because you're on a high speed connection, it doesn't necessarily mean you're on a GOOD connection.
Do some research it may be time to change providers, You can get some really cheap plans out there, but they usually come at a price, odds are a $9.95AU ADSL2+ Unlimited plan will have worst connection for games than a $60AU traffic limited plan.
You might have high speed and can download fast, but with games it comes down to how direct you connect to the host/server in milliseconds. A high ping will not be helped by a fast download speed.
Technical Stuff
Get to know your hardware, knowing what your modem/router can and can't do is just as, if not more important than how fast your internet is.
Wired Vs Wireless
Many people have wireless internet these days, while better than in the past it is still not as good as any wired internet. It's open to interference and drop outs like any wireless device, like mobile phones for example.
It might be convenient having no wires laying about, but rest assured you're going to get a more stable connection using cable, or a land line based Broadband service like ADSL2+. If possible try and avoid wireless internet and ethernet connections when gaming.
Hardware: Modem/Routers
Read some reviews about your hardware, some modems are better than others, if you take your gaming seriously it might be time to upgrade. What are it's features? Can you easily modify most of it's settings?
Many casual gamers do not realise via your browser, you can open a menu on your modem where you can "tweak" things. It usually means having to enter an IP address into the browsers address bar. For example a D-LINK modem it might be 10.1.1.1 a Netcomm it may be a 192.168.1.1
It varies with make and model, check the manufacturers website, or the manual that came with it for more info on how to get to the menu.
When accessing it, you'll be asked for a user name and password 99.9% of the time it will be by default:
Name: admin
Pass: admin
Open NAT
Do you often get a message form xbox live stating you have a "moderate NAT" and that while you can use live and play, you may experience problems like with voice?
If so you need to access your modem and make the xbox an Open NAT
Here's a brief article on it.
http://www.g4tv.com/thefeed/blog/post/677706/tip-open-your-nat-for-a-better-xbox-live/
Again google some thing like "open NAT xbox 360 (modem model and brand here) guide" or "configure (modems name and brand) for xbox live"
There are a tonne of guides online to rectify this, and as every modem is different the settings will be different and it is important to find one that matches your hardware.
Adding your xbox to what is called the "DMZ" can fix many problems most xbox live users have.
Try and avoid using an automatic IP and manually assign one to your xbox, because you will need a locked in IP for the DMZ to work to avoid having a new IP assigned every time you reboot your console, which will make your DMZ and open NAT fail again.
Well that's it, I realise it's not the most indepth guide but as I said every ones setup is different and it's impossible to get too detailed, this is more designed as a starting place. With a bit of research and tweaking you could have the best xbox live experience since owning the console.
and if you don't know what you're doing or it seems complicated ask a techy friend for help, everybody has at least one person on their friends list who knows what to do ; )
Feel free to add any advice and links to this and let's try and make every ones Crysis 2 experience better.