Here's some simple and not to spoiler-heavy tips and tricks for playing hardcore.
- Maintain your weapon - the better it's condition, the better the chance of you killing hostiles fast
- Maintain your armor - you'll need the protection
- Watch the ammo you accumulate - it has weight now. Only bring what you need.
- Bring some water and food. Loosing stats cos you're half-starved and thirsty is a foul way to die.
- Bring antivenom. You'll need it sooner then you think.
- Check the compass for red marker and use scopes/binoculars to scout before heading into trouble.
- Even if you don't use guns as weapon skill of choice bring a sniping rifle. Even with sucky skills I am often able to snipe far away hostiles and reduce potential troubles.
- Watch your weight. Nothing is worse then dying cos you couldn't evade.
- I highly recommend getting a secondary weapons skill - explosives is really useful for dealing with grouped enemies and crippling their limbs.
- Target limbs to cripple. Shoot arms to reduce incoming damage (if they can't shoot effectively, you gain time), shoot legs to reduce their speed, shoot heads to kill quickly.
- Use your skill points effectively. Main weapons skill, speech, science, lockpicking are all purpose skills everybody needs. Repair isn't necessary, but helps and adds extra options. Survival allows you to refine a lot of items you find for bigger gains and larger pay. It also gives you access to perks that make survival in the wasteland a tad easier.
- Shooting and killing gives you bonus perks that add bonus damage. You'll need it.
- Get a follower or two. not only add they firepower, but the extra storage capacity is immensely helpful as well.
- Talk to everyone. Learn as much as you can about a given situation before making decisions.
- Making friends with one faction usually ends up pissing off another.
- liberally employ save games. Changing from one cell into another (e.g. entering a house) prompts auto saves.
- Explore carefully.
- Beware of Deathclaws. Seriously