When traveling by car, always lock all the doors before you set off, as it is not uncommon for opportunist thieves to try to open them and snatch belongings. For the same reason, keep bags and valuables out of reach and out of sight.
It is highly recommended that you have someone with you at all times that is a local besides while being in your hotel. Taxi drivers will usually stay with you too when going to local shops and making quick stops and will serve as your translator if you get a good one. Be careful with any equipment you have with you such as digital cameras and video equipment. Be careful also of what you take pictures of. Even if they say no photos only at the airport and of government buildings, a lot of times the police and UN people will get upset if you are taking videos at other places where technically it is supposed to be ok to do. Just be sure to have plenty of locals with you that know what they are doing and can provide security and a way out if you get stuck or in trouble. Follow their advice and pay attention when out and about. When in doubt about taking a photo of something don't until you get very clear instructions that it is ok. Don't keep cameras in open view unless you've been cleared to take a photo. Also be equally prepared for hostility and positive reactions when taking photos.
If you are approached by people claiming to be police, be wary. If they are not in uniform, they are probably not police but are most likely hoping to relieve you of your money and valuables. A common tactic is for a group of men in a car to show a fake police identity card and ask you to go with them to the police station. Do not get in the car; just walk away. Be prepared to run. Never lose your temper, but keep negociating in a friendly way; in the end, they will give up.
Recent road scams have included a group of fake police officers in an unmarked 4x4 vehicle that will pull over unsuspecting people driving alone in cars, then forcibly take them in to their vehicle, drive them out to the country, rob them of everything and leave them stranded. While the main targets have been UN staff in obvious white UN vehicles, all foreigners driving should be wary of this group or others operating like them. For general safety, people should never drive alone in vehicles, especially after dark.
Don't drink the local water. Bottled water seems to be cheap enough but sometimes hard to find for a good price. The best way is if you are staying in an upscale hotel that provides it with the room just tip the housekeeping staff to get extra bottles put in your room usually if you tell them while giving them the money that works the best, and after the first 2 days of asking for the water you usually don't have to worry about telling them anymore, just give them the $5 a day.
Make sure you have all required vaccinations - i.e. yellow fever, typhoid, etc.
Mosquitoes can be a problem in the entire city. Malaria medication should be taken.
money/currency
The US Dollar USD is the prevalent currency for most transactions of any significant quantity. Payment in USD for a purchase will likely return change to you in USD for denominations greater than $5-$10. Lesser amounts, and any remainder, will be paid in Congolese Francs approx 900 CF per 1 USD - as of 22 MARCH 2010.Credit cards are not widely accepted -- do not count on them to keep you afloat. Only major hotels ie The Memling and some Supermarkets will accept them if there are no connectivity issues. Cash can be withdrawn from the PRO CREDIT Bank with a valid international VISA ATM card. Denominations are distributed in USD and/or CF. Ensure that you have notified your bank of your intentions to travel in order to ensure seamless and unhindered use of foreign ATMs.