I'm going to do something unusual and post from the other side of the DM's screen today. The topic today is survival. How to manipulate the odds so that your character has a decent chance of survival. Now if your DM is consistently pitching softballs at you while you trundle along the railroad, this advice may still be of use and may even allow you to take some measure of control over the situation. This is all stuff I've picked up playing D&D games and all of the disastrous encounters I've had to contend with.
#1 - No Backup Weapon, No Ranged Weapon, No Light Source, No Means Of Igniting Said Light Source, No Future!
Unless you've got one of those aforementioned softball pitching DMs, there is a simple method of ascertaining which members of a beginning 1st-level party are likely to die first.If someone doesn't have a second melee weapon; a ranged weapon with an adequate supply of missiles; no light source and/or no means of igniting said light source, they are going to be among the first to die. They may not necessarily die because they don't have those items (although that is a possibility), instead it's a symptom. Such types tend to be the characters that automatically charge superior forces or practice kleptomania while in the town that is the party's staging area. Although it is always pretty damn funny when someone dies because they went on an expedition into a giant underground labyrinth without thinking to bring a tinderbox and torch. The necessity of food and water is situational, but you'd be surprised how many folks go out into the wilderness without enough food.
#2 - Always Have An Escape Route And Always Be Willing to Cut Bait And Run (Before Things Go South)
This should be common sense, but in practice it's often painfully not practiced. Never start an engagement with a foe without a viable escape route. If possible work out an escape plan before the battle. Save spells and magic items for escaping an engagement. Once things looks like they may go bad, immediately begin an orderly withdrawal of the party. If some hothead ignores the withdrawal leave him to his fate. If one of your buddies if being cut to pieces and rescue looks unlikely, leave him to his fate. There's always the chance you can ransom or rescue him or recover his body. Always make sure someone in the party is slower than you. In AD&D I love banded mail, although it has an armor class of 4 compared to 3 for plate, you have a movement rate of 9" in it instead of 6" in plate. My banded mail armored fighter will be running away while Johnny Platemail is getting eaten by a Tyrannosaur.
#3 - Surviving A Battle Is Easier Without Democracy
You know how military forces or swat teams always have a clearly defined leader who gives order that the team follows? They do that because it works. Whomever has the best tactical sense in the party should be made into the "Battle Leader." If the party has a leader or a face that isn't tactically acute, well they still can be the leader, but the Battle Leader should be deferred to in combat situations. The party has a far better chance of survival with someone in charge. If someone doesn't want to get with the program and puts themselves in peril as a result see #2 above.
#4 - Upgrade Your Tactical Skillset
This especially applies to "Battle Leaders." Tactics work, learn them. Sun Tzu's The Ancient Art of War, computer wargames, Counterstrike, Chess, Paintball, Hockey, Guerrilla Warfare, what have you. There are many ways of learning tactics, which tend to be generally applicable in conflict situations, if you pay attention you can learn a lot. There's a ton of useful practical knowledge about controlling the battlefield and mitigating asymmetrical situations embedded in such subjects. Choose the battlefield, let the enemy come to you, attack the invulnerable foe where it is weakest, commit reverse mental torture upon your foes.
The above advice may be too much or inapplicable for some player's/groups, you may just want to have fun and bash some orc skulls in. You may be only fighting "balanced encounters." Obviously if you're not interested in subjects such as tactics it can be kind of pointless to study them in order to play a hobby game better. But if you want to be a better D&D player or if you're finding your party being overwhelmed by your foes, this stuff will help you.