I am in no way an authority when it comes to the wonderful little machine we all treasure, the T2i, but I have enough hours behind the lcd to comment. I have seen countless threads across the web asking how to shoot with the T2i and get the most out of it. Maybe we can all add some tips that stand out to you and get a little beginner to advanced user guide going. If any of my or other information is incorrect kindly correct it

First and foremost if you really want to get the most out of the T2i look into magic lantern. Instead of telling you how great it is, which it is great, (just look on this board and one of the several threads discussing it) I'm going to tell the skeptics that you don't actually install the program onto your camera. Other than a small easily removable buffer type application, the program lives on your SD card. One thing I can't stop being excited about though is the Kelvin white balance in the newest build. K white balance will make your filming so much better, and revolutionize your low light shots! (unless of course you always use manual white balance which is just such a pain).

Focus: the only way to be good at focusing with a dslr is practice practice practice. One tip I can offer that I use nearly every time I hit the record button is to start as far out of focus as possible and do a 1-2 second focus pull into focus. This achieves two things, most importantly it allows you to really see where "in focus" is with your camera. Since cutting in post is so quick and painless its really not a big deal when editing. Secondly, if you do this with all your shots you will quickly realize this is a filming technique used since the inception of film and you will often utilize it in your final cuts. Play with this technique and I guarantee you your focusing skills will grow.

ISO: this is something I stole from an article by Shane Hurlbut, a bigtime director of photography (think drumline, We Are Marshall, Terminator: Salvation) who started using DSLR's exclusively. Anyway, Canon DSLR's have native or "clean" ISOs which is basically the ISO range sweet spot. Those numbers are 160, 320, 640, 1280, basically the native iso being 160 and from there multiples of two. So ISO 640 would actually look better/have less noise than ISO 400. Now I'm sure some of you are asking, but the T2i doesn't have those ISO's. With magic lantern, IT DOES =-)

Aperature: Wide open may give you the best low light performance, but try to avoid it. Somewhere between f/4 and f/8 is the sweet spot and you really will get the best results. Also a little tidbit also stolen from Hurlbuts article, f/5.6 on a 5d mark II is equivalent to wide open on a 35mm movie camera. The 5d has a considerably larger sensor then the T2i but that was still interesting to me, guessing the T2i would sit around f/3.5.

White balance: I mentioned white balance earlier. Particularly with low light shots and high ISOs, white balance is key. When shooting in low light, it is essential to have your white balance dialed in. Do this test, shoot low light iso 1600 under normal indoors tungsten or fluorescent lighting with auto white balance. Now shoot with dialed in manual white balance, maybe using Kelvin white balancing with magic lantern, and compare. The difference is night and day.

I'm sure for many of you this is all information you have known for some time now. If thats the case, please offer a tip or two that we can all start using. Hope this lists grows!!

Thank you very much for your thread!

ML: have you had any problems? I read some people uninstalling it because they had trouble with it. I haven't tried it yet because of that. I would really like histogram and manual white balance.

Focus: agreed, just practice, practice and practice. With time you get the right eye-hand coordination combined with a little bit of perception on where exactly focus is. I think a z-finder or similar isn't actually a MUST in indoors, but it is on outdoors. Forget about focusing on a sunny day if you don't have a loupe or shade or whatever. Even forget about exposing, I mean, you really can't see a thing. That's a MUST, some kind of shade or loupe to use when being on a sunny outdoor.

ISO: are you saying that if I install ML and use ISO 640 instead of 400 I will have more brightness and less noise?... ?...

Aperture: I think that is related to each lens and not the camera? I don't understand exactly the point, specially when you compared the 5D to 35mm.

Ivan, I haven't had any problems with magic lantern at all. I think a lot of people don't like it because when in the menu there is a constant flicker which doesn't bother me. And, if you gave 5,000 people something great for free, usually the only ones you hear back from are the ones who aren't happy with what the got. I can assure you there are countless ML users out there loving it who just aren't chiming in.
Yes, if you use magic lantern, ISO 640 is going to look better than ISO 400 and naturally you will get more "light" to your sensor.

Thanks Luke, very good points to remember and I agree that the extra features using Magic Lantern considerably enhance an already good camera.

Aliasing is still an issue. It can be avoided by shooting selectively but this can be quite limiting in some situations. Lets hope Magic Lantern can address this in the future.

I had problems getting Magic Lantern running via a Mac but it's more straight forward using a PC. Anyone who wants to try should exactly follow the installation procedure or risk bricking their camera. I'd suggest don't do it unless you understand the instructions.

If you get it running and like the features - donate!