Take warm clothes in the winter
Luggage and bags: We had a great back, and small rucksacks, traveling first class that was fine, but if you go coupe it can be to much
Clothing/Shoes/Weather Gear: Buy winterboots in Russia, lined with fur, and good winter coats. A hat, a good woolen one, or a fur one is neccesary, and good warm gloves. We went in the winter and in Ulan Ude it was -40 c So tkae thermal underwear with you too.
Toiletries and Medical Supplies: Take toilet paper, but most of the time there is toilet paper on the trains, but not on the public toilets.
Miscellaneous: Ladies, take waterproof mascara with you. In the winter your eyelashes freeze, so when inside they will thawn, and run if you have not used waterproof mascara.
Toiletries and Medical Supplies: IF YOU GO CAMPING water purification pills are useful although I often drunk water from Lake Baikal without adding any.
Photo Equipment: It is impossible to find APS films in Ulan Ude. Choice in film speed is limited for 135mm films but you can find most common brands and speeds.
Camping/Beach/Outdoor Gear: MULTIFUEL STOVE is essential if you go camping. I could only find car gas in Buryatia (car petrol, for our British friends).
FOOD: DO NOT worry about bringing along a lot of food. The grocery stores in Ust Barguzin and the Barguzin valley have plenty of food. For the veggies, just buy some from villagers (see picture). Some people will want to give it to you and won't accept any money. You can always slip a bit of money in their pocket or give a little souvenir from home.
Miscellaneous: PICTURES OF YOUR FAMILY, FRIENDS, ETC... Even if you do not speak much Russian, showing the pictures is a great way to share a good time with your hosts or the nice people you will meet on the train. COINS FROM YOUR COUNTRY: I met many people who collected them and were glad to get some Canadian, French or Japanese coins I had.