Comfortable, rubber soled shoes. Bring an umbrella that can withstand the wind
Miscellaneous: An absolute necessity is to download the free map (in color, preferably) from Use-it. It is the only guide you need to Leuven unless you know people there. Other Belgian cities available, too.
Luggage and bags:
What do you need? Coming from China perhaps, but I have found clothing and shoes to be very expensive here in Leuven. Bring the stuff from home.
Clothing/Shoes/Weather Gear: You must bring a jacket regardless of the time of year you visit plus an umbrella as it rains alot. Good walking shoes are a must because the city is really well designed for getting out into nature on well marked paths. You can pick up walking maps at the In and Uit Tourist office. Will add the address soon.
Toiletries and Medical Supplies: You can get anything you want here. There are chemists that sell just about everything PLUS they usually speak pretty good english. Supermarkets are plentiful. In the main street, near the FochPlein (city centre) there is a MATCH supermarket where you can also buy pre-made sandwiches but for only a tad bit extra I suggest going into a deli and getting one made fresh.
Coffee shops are plentiful. If you are staying for any amount of time then get the customer reward cards offered at places like Foodmaker and Panos.
Photo Equipment: Plenty of shops in Leuven for camera / video equipment. The biggest (and expensive) is FNAC which is a chain in Belgium. It is on the main road between the train station and the Foch Plein.
Camping/Beach/Outdoor Gear: No Beach, don't know about camping. Lots of day trips though. You can hire a push bike that can accomodate three or four kids plus an adult or two... I know, you should see them going past. I always stop for a gawk. You can rent these bikes.
Miscellaneous: The buses are great. Buy your ticket at the bus station (big red building next to train station) and save money. On the bus you can buy for 2 euros but it is 1.5 if bought beforehand. If you are staying any length of time buy a monthly ticket. It cost 26.5 euros and is fantastic value as you can catch any DeLign Bus ANYWHERE anytime in Belgium. Three or fours days of getting around on buses and you have covered your costs. You need an address so just give the address of the hotel you are staying.
Bring comfortable shoes for walking. There's no point in driving a car into the city - you can easily do everything on foot. Just bear in mind there are many cobbled streets in Leuven, so if you want to venture off the beaten path a bit, your feet will kill you at the end of the day unless you wear something suitable, like sneakers.
The weather, unfortunately, is highly unpredictable here - like in most places with a moderate sea climate. We do have an occasional heat wave during the summer or snow during January/February, but not for extended periods. Most of the time, the weather here is cloudy but mild and enjoyable. However, keep in mind it does rain fairly often and it can get chilly in the evening, even during spring/summer.
To be on the safe side, it's best to always take an extra sweater with you if you plan to spend several hours walking around the city. An umbrella might come in handy, as well - but when it rains it's usually not for hours on end - it's not *that* terrible :)
Clothing/Shoes/Weather Gear: I went to Bruges with a friend from Chili. Apperently they are not used to fast changing weather overthere. We had rain, sunshine, snow, some more sun, storm and again sun all in one day. My friend, who had never felt snow, went completely nuts and thought the apocalyps was near. The belgian wheather can be very unpredictable. Belgian wheather reports are notoriously inaccurate (we only have a small army).
rainy weather gear: rather a water-repellent hat than an umbrella. That leaves your hand for shapshoting.
Photo Equipment: telelens: you may need it for the close-ups; film rolls: you can always buy them there; memory sticks
Miscellaneous: The guided tour we had at the University Library was done for free (would check whether it usues to be FREE or NOT). We brought, though, a box of chocolate for Jan, the guide. He doesn't ask for anything but it's well deserved.
Luggage and bags:
In Belgium sometimes it rains, even in Summer. So you need surely an umbrella.
Clothing/Shoes/Weather Gear: Good walking shoes, for walking in the old streets.
A warm sweater.