Tips3

defuser: Defuse kit (Counter-Terrorist)
$200. This device can help Counter-Terrorists defuse the bomb twice as fast on bomb/defuse maps. It is relatively cheap so it's a good idea to pick it up if you're a Counter-Terrorist. When a player who has purchased one is killed, the defuse kit falls to the ground (it appears as some belt pouches) and can be picked up by other Counter-Terrorists who do not already have it. You'll appreciate it when you're pressed for time.

nvgs: Night vision goggles
$1250. Night vision goggles allow the wearer to see in total darkness. Activating and deactivating the goggles makes a distinctive noise that can be heard by nearby enemies, so beware. In normal light, however, everything is washed out and it can be hard to see. It's expensive, but quite valuable on the particularly dark maps.

shield: Riot shield (Counter-Terrorists)
$2200. The riot shield prevents you from holding a primary weapon, but while having it equipped you can alternate between using it as a shield and poking your secondary pistol or grenades you are about to throw out to the side. The shield, while used to block incoming fire, deflects all rounds; while used, though you cannot return fire. The riot shield can come in handy when you're mainly facing off against the enemy in one area and letting them waste their shots at a target while they get flanked, but its tremendous expense limits its usefulness.

Bomb (Terrorist)
On bomb/defuse maps, one Terrorist starts with the bomb (which appears as a backpack on his model). That Terrorist must bring the bomb to a bomb site (there may be more than one on a given map), plant it, and ensure that it detonates properly. The bomb can be dropped (either deliberately or by its carrier getting killed) and picked up by another teammate; Counter-Terrorists cannot retrieve the bomb (although they can of course guard it). When you spawn with the bomb, you should consider it your primary purpose in life to see that it goes off.

vest: Kelvar vest
$650. As in most first person shooters, armor is essential to Counter-Strike. Especially in Counter-Strike, you might say, since with fairly realistic weapons and damage, only a few hits on an unarmored target will bring him down. Only buy the Kevlar-only option if you can't afford the Kevlar-helmet combination.

vesthelm: Kevlar vest and helmet
$1000. As with normal Kevlar, but also including a helmet, which will stop one round (with a horrible clank sound and a severe distortion of view for a few moments) which would have otherwise hit the head; any unprotected headshot is fatal. Armor-piercing rounds, such as that from the AWP, will still land a kill on a helmeted head, but you can't beat an extra shot at life. Don't leave home without it.

                                                          Action   Reward/Penalty
                                        Rescuing a hostage   $1000 for individual, $150 for teammates
                                            Killing a hostage   -$1500 for individual
                         Touching ("using") a hostage   $150 for individual, $100 for teammates
                                            Killing an enemy   $300 for individual
                                         Killing a teammate   -$3300 for individual
                      Terrorist win by bombing target   $2750 for teammates
                Win by elimination on hostage map   $2000 for teammates
         Win by elimination on bomb/defuse map   $2500 for teammates
         Counter-Terrorist win by defusing bomb   $2750 for teammates
        Counter-Terrorist win by hostage rescue   $2000 for teammates (not counting hostage bonuses)
                                 Surviving hostage bonus   $150 per hostage for teammates
                                  Hostages rescued bonus   $250 per hostage for teammates
                                  Either team loses round   $1400 for teammates
Either team loses over two consecutive rounds   $1400 + $500 per additional round for teammates