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This is a simple strategy to help you survive in the Mojave Wasteland:
1) Invest skill points in Small Guns and Sneak, and make sure to start out with an average or high perception attribute.
2) Concentrate on obtaining rifles, pistols, and other semi-auto or bolt/lever-action weapons, along with ammo for them.
3) As you travel through the wasteland, constantly press on the VATS button as you survey the environment; eventually, you will zoom into an enemy or creature. Now, rather than shooting in VATS, quickly switch to your weapon's ironsights and fire off a shot,
4) Provided that the enemy isn't rapidly moving or behind an object, you should hit them. If you're hidden, this will be a sneak attack critical, which is quite useful for taking out armored enemies when you're at an early level. In other words, with sufficient stealth and small guns skills, you are guaranteed to get a hit at long range using this tactic, even when your chance to hit in VATS is below 10%.