Lithuania is generally a safe country. The crime levels are on par with those in the USA. However, unlike the USA and many other countries Lithuania has no unsafe districts or ghettos and the crime is spread fairly evenly. Districts with many bars (e.g. Vilnius Old Town) may be less safe at night due to drunk people but common sense helps.
Lithuania is sheltered from natural disasters. There are no deadly earthquakes, volcanos, tsunamis, hurricanes or floods. Massive evacuation due to natural disasters is never required. Winter cold and summer heat takes some tall but mostly among the homeless.
However, history has proven that aggressive neighbors can be deadlier than any natural disasters. Lithuania stands between East and West and in 1795-1991 suffered long occupations and genocides by the great powers, primarily Russia (a third of Lithuanians lost under 1940-1941, 1944-1990 Soviet occupations alone). While a foreign invasion may still be more likely in Lithuania than in the USA or Western Europe, the chances are slim (last act of aggression took place in June 1991 when Russian soldiers massacred six Lithuanian customs officers).
On the positive side, no people have been killed or injured in terrorist bombings in the entire Lithuanian history.
While a decade ago more drivers would disobey rules and become a danger to others, campaigns against so-called "war in the roads" have curbed this (the accident rate is now similar to other European countries).
Given all of the above, the most likely nuisances for a foreigner in Lithuania are not outright crime or disasters but falling into some sort of tourist traps. Don't worry: Lithuanians are quite introverted and won't come to solicit.
That said, the group of people most notorious for cheating is the taxi drivers. A foreign tourist may be overpriced 10 times and more and some drivers are not even negotiating; out-of-town Lithuanians are also overpriced although less. Therefore it is suggested not to use taxi services in Lithuania.
In the unlikely event one gets into trouble in Lithuania and would seek outsiders' help, he/she should clearly indicate so (by asking / screaming). Lithuanians tend to be libertarian-minded and stay out of other persons' business as long as nobody gets harmed. So, for example, a streetfight is relatively unlikely to be reported to authorities (as it would be assumed that both parties want to fight).
There are some beggars in the main tourist areas (Vilnius and Klaipėda old towns) who may approach you. Never give them anything: the ones approaching tourists are not poor but rather use this as a lucrative job. They earn sums larger than an average salary as foreigners frequently hand out sums of money based on the prices in their own homeland while in Lithuania they are lower. These beggars have invented stories which they could tell in multiple languages. Take note that Lithuania is richer than most of the world; there is an effective social security system and malnutrition is unheard of.
Should you encounter problems 112 is the emergency phone number (as in the rest of the European Union).
Healthcare of Lithuania is of a formidable standard with numbers of doctors per 1000 people larger than in most Western societies. Hospitals are well-equipped to perform even the most difficult surgeries. The doctors are well-trained and sought-after by Western hospitals.
For Lithuanians and people of the European Union, most medical services are free of charge. However, corruption is rampant, meaning that a person with relationships among doctors (or a bribe) may get a preferential treatment bypassing the queues (which may get long, depending on location and procedure). This used to be the norm in the Soviet Union when all goods and services were in theory equal-to-all but in reality depended on bribes and relationships; today it declines.
This, as well as Soviet "patient-is-always-wrong" attitudes in some public hospitals (also declining), makes a part of the population to pay full price at the private clinics (even though they are still subjected to massive compulsory public healthcare taxes). This heavily depends on a specialist: nearly everybody visits a private dentist or gynecologist just as nearly everybody uses the public hospitals for major surgeries. For a foreigner private hospitals may be less of a hassle in all cases especially if one has an insurance coverage for them. Even without it, many procedures may be cheaper in Lithuania than the West (dentistry, plastic surgery). Lithuanian emigrants come back home to perform them.
If you choose public hospitals the best ones (and the largest) are in Vilnius and Kaunas.
Lithuania has a wide range of health resorts and spas, especially in Druskininkai resort.
There is generally no need to get any vaccination before going to Lithuania. Major infectious diseases such as Hepatitis B, Hepatitis C or HIV are extremely rare.
After Lithuania joined the European Union (2004) it also ascended to its Schengen Treaty. This treaty establishes a single Schengen visa to enter all the member states. Within the Schengen area, there are no customs nor border control meaning that you could easily combine a trip to Lithuania with some neighboring countries (Latvia, Poland).
One may apply for a Schengen visa at any Lithuanian embassy or consulate. Furthermore, if there is no Lithuanian embassy or consulate at your country, Lithuania is represented by an embassy or consulate of some other EU-member state; a visa could be applied for there.
While Lithuania would be willing to extend visa-free regime to more countries the Schengen regime means that Lithuanian visa regime has to be similar to that of Western Europe (which is plagued by illegal immigration and therefore is reluctant to grant visa-free regime to most countries except for the richest ones). Japan, South Korea, Taiwan, Malaysia, UAE, Brunei, Hong Kong, Israel, Macau, Australia, New Zealand, USA, Canada and most of Latin America are the only areas outside Europe whose citizens could travel visa-free to Lithuania. On the other hand, nearly all Europeans can do this with the exception of Russian, Ukrainian, Belarusian and Turkish citizens.
Schengen visas are short-term only; a longer visa is called "national" (and must be applied at Lithuanian embassies/consulates) but still allows traveling inside all Schengen area. If you are just transferring at the airport you need no visa unless you come from a migration-sensitive country (some Asian and African countries).
In general, any public places in Lithuania may be pictured and taped for private use, while in private areas the owner decides what could be pictured.
Under the Soviet occupation, photography was heavily restricted even to the few that owned cameras. Most of these limitations were abolished, but it remains forbidden to take pictures at the international airports. When taking pictures of other key infrastructure (especially the railways) one may still get some interest from the security, although it is no longer that restricted.
Private shopping malls, marketplaces, casinos and nightclubs usually ban taking images - while this policy may be not explicitly stated anywhere, the security enforces it. While it may be possible to take a quick selfie or picture your friends without generating attention, any longer "photo shoot" will surely attract it. Chain stores tend to especially hate when their price tags are pictured, even if on the background.
Most museums allow photography but some forbid, while an even smaller minority levy a fee on every camera. Usually this is specified near the entrance (otherwise, you may ask).
In the case of live events (concerts and professional sports), the rule of the thumb is that only the most expensive, important and popular ones ban taking images. E.g. it will likely be forbidden to take pictures during official international basketball games but allowed during friendly matches or national league games.
Lithuanians usually don't care that they are photographed in public and they don't expect anything in return for it. Photography of private areas (even if visible from public zones), such as yards, may cause concern - but it is not very likely. The overall rule of the thumb is simply not to be too intrusive and take pictures from a distance or, if a close-up is needed, then ask the person.
It is not advisable to take pictures of drunk people (especially in the evenings) as they may be looking for a fight.
In case you want to publish pictures more stringent rules may sometimes apply. Some museums that allow free private photography impose a fee on those who want to publish images. Additionally, it is forbidden to publish pictures of people without their permission (even if taken in public) if those pictures show them in compromising situations or are used for advertisement.
Specialized photo stores became rare after digital imagery displaced the analog one. However, memory cards, batteries, and other photo materials may be easily acquired at electronics stores, common at shopping malls.