If you could recommend 5 things

[geotography]

All of the above; and a quality tripod.

[johanmw]

1. Bag
2. Tripod
3. For your camera i would get a battery grip (i just got one, and i'll never take it off my camera again) Your camera will get bigger, you get the option of using aa-batteries, and a better grip on the camera.
4. Flash (Expensive, but well worth it)

[rediguana]

In now particular order - 50mm lens, flash, tripod, bag and spare battery.

[caine22]

1. New lens. I have the XTi as well, and i got a 17-70 2.8-4.5 Sigma and I love it.

2. Filters. A UV and circular polarized for sure, neutral density if you want lime lapses in daylight.

3. Bag. I do not have one yet, and it is a pain to try to fit even the few things i have in my pockets.

4. Tripod.

5. Lens cleaning stuff. A dust puffer and lens cloth at the very least.

[Taallyn]

1. Flash
2. Circular Polarizing filter
3. 50mm f1.8
4. Lens Pen (nice, easy lens cleaning tool)
5. "Understanding Exposure" by Bryan Peterson.

But most of all ...

Shoot pictures. Nothing helps more than experience. Shoot something. Change the settings. Shoot it again. Compare the pictures to see how the settings affected them. Shoot even more. All of the gear in the world won't help if you don't practice.

[guy-montag]

1. Joining Project 365 - http://www.flickr.com/groups/project_365/ - practice makes perfect, and shooting a photo every day for 365 days in a row works *wonders*.

2. Learning from mistakes, and making them!


On the practical side, a tripod can be handy for photos where you can take your time, and a 50mm prime lens is also very handy, probably the best 'bang for your buck' you can get in a lens. A remote is also something I've enjoyed having, and a reflector and a speedlight / flash if you really start getting into it.

[laepelba]

I would have to add "monopod" to your list! It's fabulous for use in sports photography when you're using a long lens. Especially indoors where you've got longer shutter speeds and might be susceptible to hand-shake.

[OU1247]

A BIG THANK YOU to everyone for the advice.
I ordered the 50mm lens and LOVE IT!
What sharpness! Now for the card reader and much much more!!!!

[JFSanders]

Everyones got you pretty much covered but I would second the books on light, exposure and composition. Once you read those you will have a clearer understanding of what you need.