Loving it, played about 20 hours so far. Got to level 14 last night.
Being deliberately sparse with my skill points, spreading them around, sampling a little bit of everything but I've decided that power armor is not for me.
I found the first few levels (1-5) very easy, the next few (6-10) brutally difficult at times then things started getting easier as I upgraded my guns & got better at sneaking.
My hints thus far;
1. Spend at least some of your upgrade points on the +20% damage with . It's boring but you need it.
2. Go back to drop off all your junk often, you'll be filling up your inventory fast. Subsequently, don't start with a very low strength score, you'll regret it.
3. Watch out for mercs with big boys, they will literally nuke you in the face from 5yds with no sense of self-preservation. Find the high ground with them so when they shoot & miss it doesn't hit the ground right behind you & kill you anyway.
4. Quicksave often.
5. Make use of mines, chems, terrain. The wasteland is no place for honourable duelling!
6. Save your stimpacks for actual injury where possible, eat food, drink water or nuka cola the rest of the time. These can't cure your broken limbs.
7. If you're overloaded, use a buffout so you're unencumbered then you can fast travel back to your stash.
8. As has already been said, shoot them IN THE FACE. It works well, unsurprisingly.
9. Deathclaws... just don't unless you've got ammo to burn, they're not really worth the effort it takes.
10. Rapid Fire guns are a great way to waste ammo. Yet to find a reason to use one.