Huge post filled with tips and musings about playing DayZ
DayZ Offical Site
Chenarus Static Map
Chenarus Interactive Map w/ Loot Locations
Wictro's DayZ Help Center
Chernarus is huge, use one of the maps linked below to get an idea of where you are, all of the signs in the game are in Cyrillic so if you aren't well versed in Slavic languages the designers of the game have been nice enough to include both the Cyrillic and English versions for all of the locations on the map.
The engine for this mod ARMA II is an ultra-realistic military simulation shooter. All of those fancy words mean a few things for you, the DayZ player... The most important thing to remember is that when you fire a weapon it makes noise and noise will attract Zombies and (usually dangerous) Players.
Different weapons make different amounts of noise ranging from the incredibly loud(such as the incredibly common Lee Enfield rifle) to fairly silent(the Makarov PM pistol you start with) to the completely silent(Compound Crossbow).
Another important thing to consider is the weapons physics, in DayZ when you fire your weapon the bullet actually leaves the barrel of the weapon(as opposed to the rough approximation you are probably used to from other shooters like Halo and CoD), each round for each weapon has its own velocity and gravity is in effect. To counter this most weapons that have any significant range also have a scope and most scopes can be adjusted using the zeroing controls in game.
Most weapons require multiple shots to the chest to put down a zombie but all weapons only require one carefully aimed-often missed shot to the head to send a zombie back to the grave. Players however seem to be a little more difficult to kill, often taking multiple headshots to completely put them down.
Always remember that desperate times call for desperate measures and almost every person has turned into a complete and utter sociopathic maniac willing to kill you just for being there, be aware that hiding is the best way dealing with another unknown player. Often times other players are only going to save you from becoming zombie food by putting a bullet in your head and liberating you of your precious beans.
Lastly keep in mind that being ultra-realistic means that when you get attacked you will most likely bleed, when you are cold you very well might get sick, when you fall you will either die or break your legs, when you are injured you may be in such intense pain or a state of shock that you screen will shake and your aim will be awful. Also, for some reason swimming may make you lose your backpack.
You should immediately get off the coast and head to a small town, staying away from Chernogorsk and Elektrozavodsk for the time being as they are bandit and zombie heaven. You will want to crouch walk whenever you are anywhere near zombies, you can crouch using "C" and walk using "SHIFT", you may crouch run when you are not super close to zombies but I would not reccomend it until you get used to how the sound and sight mechanics work.
Find a barn or a house without too many zombies near it and carefully crouch walk your way up to it. Barns, stables and houses all provide the basic starting supplies you will need to make your way into the larger cities and get the phat lewts within. You should get used to using the "ALT" key to look around freely without turning your character(useful when walking carefully), it will save your life when you walk near a zombie you didn't notice before. The most common things you will find in these locations are basic weapons(Winchester 1866 shotgun, Compound Crossbow and Lee Enfield rifle.), ammunition, bandages, food cans and drinks, misc supplies(hunting knives, hatchets, flares, chemlights and occasionally flashlights) and most likely you will find empty cans.
My personal preference in starting weapons are Winchester>Crossbow>Makarov>Enfield, the 1866 shotgun is the best balance of power/sound/availability, the crossbow is silent but has a long reload time, the makarov pistol you start with is fairly quiet and ammo is everywhere and the lee enfield while being powerful is one of the loudest weapons in the game attracting zombies from several buildings away at times.
Once you find a good weapon, ammo and food, you may want to try to head into a larger city, just be aware that you while your impending death at another players hands is always looming, it is most prevalent in a large city or airfield. Your best bet would be to look at a detailed map of each city, plan a route, carefully work your way through it and get out as quickly as possible, stay out of the main street and squares as much as possible and always crouch walk/run. The key locations for a city are supermarkets(weapons, ammo, food), hospital(medical supplies), factories(random mix of basic items), churches(decent weapons and med occasionally) and in some cities military tents(basic military weapons, ammo, rarely a backpack, tons of medical supplies and chemlights).
Once you have a better weapon, some good supplies, plenty of food and water/soda you may consider getting together with a group if you haven't already and head inland to find deer stands in the woods, airfields and military bases. The best items are located at the northern airfields, military bases and cities like Stary Sabor. Make sure you have a good group and plenty of great weapons because the bandits thrive on players like us who want to raid the northern reach.