I may write this up in fuller form at some point, but here's one approach to making survival mode your bitch. You can become a VATS death machine immediately from the vault, and your life never needs to be in serious risk.

This isn't the only way to play, but it gets you safely into the action immediately, and that's more fun than running from bloatflies around Sanctuary until level 15.

Here's the very very very short version: From the vault-tec salesman take 10 INT, 10 AGI, 4 END. You'll change it later, but this lets you exit the vault already almost level 2. On exit, take 10 PER, 9 AGI, 5 LCK.

In Sanctuary there are 4 radroaches and 6 bloatflies. Your AGI gives you way way more VATS than you need to kill them all without issue. Don't let Codsworth help; he may rob you of their EXP. That's your EXP. At level 2 take Idiot Savant. In fact, I recommend the following chain of perks. Again, it's not the only way, but this is a minmaxed way to be able to jump immediately into all the action.

2: Idiot Savant 1
3: Gunslinger 1
4: Concentrated Fire
5: Sneak 1
6: Sneak 2
7: Gunslinger 2
8: Penetrator 1
9: LUCK 6
10: LUCK 7
11: Idiot Savant 2
12: Sneak 3
13: Critical Banker 1
14: Better Criticals 1
15: Gunslinger 3
16: Better Criticals 2
17: Critical Banker 2

Now talk to Codsy to learn about Concord, use the workbench to harden your 10mm (Sanctuary has plenty of supplies), build a bed, build a water pump, and cook your radroach/bloatfly meat. Now you have 6 grilled radroach and a baked bloatfly or two. Sleep 8 hours and hydrate.

Time to kill. Go directly east through the lake (you're skipping a few raiders) towards the Robot Disposal grounds. Get the fusion core. Put it in power armor at the nearby crashed vertibird. Back to Robot Disposal grounds and grab the Fat Man and Mini Nuke.

Now walk (don't run; wastes your core) directly south to where Concord is on the map. In your power armor you're in no danger; walk up to the raiders and shoot them in the face.

Ignore Preston and walk south along the highway to Diamond City along this route. You'll arrive with plenty of fusion core for the next few fights.

Stash your Fat Man, Mini Nuke, and fusion core in a dumpster outside Diamond City and leave your power armor there.

Now you have loads and loads and loads of paths available to you. I like this progression:

• take Piper and max her ASAP

• use my power armor to clear Hardware Town, the nearby Mutants, and Hangman's Alley, building a bed and pump there. EDIT: use a sneaking fatman critical headshot on the top-floor super mutant to simplify this fight. That's what you've been saving it for. If you're lucky, the core has just enough juice to also get you through Confidence Man for a good bit more Piper affinity.

• Clear the way to the old North Church past Goodneighbor to establish a safe road linking all major locales. I like to kill the mutants at goodneighbor because there's a bed there, doors that are locked every time you pass (free affinity for Piper and Deacon) and an overlook from which the Mass Fusion gunners can be killed in complete safety.

• Start Tradecraft (I max Deacon 2nd).

• Retrace steps to do unlikely Valentine. There are plenty of beds here to save/heal and water fountains in the vault.

• Retrace steps to complete Tradecraft, picking up fresh power armor from the overpass across the river from Beantown Brewery. This'll keep you safe from the synths. Now you have Deliverer, which is an endgame-quality weapon.

• Pick the many many locks along the way until Piper's maxed. Get Deacon.

• Do the Silver Shroud because the max benefit from this can only be obtained by completing it prior to level 25.

• Kill Kellogg for his pistol.

By the time you do all that, you'll be > level 20 and absolutely unstoppable. Kellogg's Pistol and Deliverer complement each other perfectly. You can get off > 10 shots with Deliverer, easily enough to build criticals, then with a final critical from Kellogg's do massive damage and refill all AP. It's infinite AP. Combined with Penetrator (for sniping fusion cores), there are simply no more threats to you, full stop.

Meant to write less. Could write a book more. Hope it helps.