The usual "don't be stupid" advice seems to be adequate. Avoid drinking the water from the tap--bottled water is cheap and available everywhere Morshinska/ÐÐ¾ÑÑÐ¸Ð½ÑÑÐºÐ°, Mirgorodska/ÐÑÑÐ³Ð¾ÑÐ¾Ð´ÑÑÐºÐ° is good. Kiev is a generally open and friendly city and stays lively until at least 11PM in most districts.
If you are female, and especially if you are traveling alone, try to take a taxi instead of public transit after 9 p.m. These are prime drinking hours and the metro and marshrutky may be crowded with drunken men. This is particularly true on the weekends. Ask a local English-speaker to call the taxi for you and get the amount of the fare in advance; drivers may greatly inflate the fare once hearing your accent.
Robberies and scams on tourists are fairly common in Kiev. The best approach is to be extremely selfish and ignore anyone who approaches you. Avoid eye contact with suspicious looking people. If you do get caught up in a scam such as the infamous wallet scam or the "Look, I've just found money" scam or even if you are stopped by someone claiming to be a policeman, simply ignore the person and walk away, indicate that you want to call your embassy or go to the next police station to get the problem sorted. That will usually shake the person off.
If you are leaving your baggage in the station, it is better to leave it with the guys in person rather than use a locker. Stories have been heard of people 'assisting' with the locker and overseeing the code, then walking off with the bag afterwards.
On the metro, always keep your belongings securely zipped as close to your skin as possible. Pickpockets are highly organised and often in gangs that know what they are doing.
There are occasional rare reports of visitors being shaken down by corrupt officials, often customs officials. Naturally, the best protection is to make sure that you stay on the correct side of the law and, if there is any question, to keep your cool and not become argumentative. It seems that the cost of an error is surrendering the object in question and paying a "fine." The officials are skilled at ensuring that people who argue miss their flights. Making, or giving the impression of making, a cellphone call to your country's embassy has been known to clear up "problems" quicker than actually paying the "fine" --- or pretend to have a very late flight :-)
Some thieves like to abuse new tourists, for example, by playing plainclothes cop. They are rarely aggressive. They will go to you only if you're walking alone and don't look too familiar with the town. A bit of resisting usually shakes them off but not too much since you never know.
There is still some corruption in Ukraine; some services might openly ask you to bribe them to process your request, and denying it might make them refuse to help you.
The people are very tolerant and it is only reasonable to assume that they expect the same in return.
Mobile cell phones: GSM 900/1800 and 3G CDMA, UMTS is used in Ukraine. This system is compatible with mobile phone networks used in Europe, most of Asia, Australia, New Zealand.
If you have an unlocked GSM phone, you can get an Kyivstar (http://www.kyivstar.ua/en...), MTS (http://www.mts.com.ua/eng...) or life:) (http://www.life.com.ua/in...) Astelit SIM card for a few dollars at street vendors which will give you a local number and free incoming calls. Note that most of those cards don't have money on their account so you may want to buy a payment card when you buy a sim card. If you don't have an unlocked phone already, new ones can be had for USD 30-40 and a touch cheaper if you buy a pay-as-you-go sim card at the same time. Incoming calls are free in Ukraine so in extremis you can just SMS/text a request for a return call for a small charge.
If you want to use 3G connection, you can get OGO! ex-Utel (http://en.ukrtelecom.ua/) for UMTS and PeopleNet (http://people.net.ua/), CDMAUA (http://www.cdma.ua/) or Intertelecom (http://www.intertelecom.ua/) for CDMA, for mid 2011 last three operators don't have English version of site.
If you are roaming in Kiev, SMS messages do work well. They are confirmed to work for most foreign networks. Do note that the size of the country and the relative low population densities of rural areas means that sometimes there might be 'black-spots' where mobiles will not work. But of course these are away from the main cities/urban areas and most of the main arterial road and rail routes also have reasonably consistent call signals.
If you are trying to call the US from your GSM phone, you may find that the access numbers for your calling card are blocked. Plan ahead and sign up with a callback service such as UWT (http://www.uwt4me.com/ **warning, lead-time required**) before you start your travels and you can provoke them to call you at much better rates when you need to make a call.
The easiest way to maintain internet connectivity if you use your own laptop is to buy a 7-day unlimited Lucky Internet callback card. They are about UAH36 at the street kiosks. When you dial in, you will be initially firewalled off from everything until you activate by visiting their website (http://www.card.lucky.net)
You may also buy wireless internet access for your laptop for about 10 UAH per day. See (http://freshtel.ua/en/) for details or just google "wireless internet in Ukraine".
Internet cafes have a good service. They usually have different types of computers with varying prices.Near the metro station on ul Khmelnytskoho on the left side at a corner there is one that is very good, open 24 hours non stop. The cheapest computers cover your basic needs, the most expensive ones are usually for hardcore gamers.
Also most foreigner-friendly cafÃ©s see "Drink" section above and a lot of fast food restaurants including McDonald's offer free Wi-Fi. Some require password to use their access point, ask waiter to get it.