The hunting rifle doesn't look like much so it was awhile before I even started using it but it's actually really powerful and good on ammo. After a while I even decided I may as well leave my assault rifle at home since I was barely using it. I've got quite a few caps and haven't been spending much so if ever you see someone selling bullets you need it's definitely a good investment.
I used to always use the VATS for shooting at people's heads but there are definite uses for shooting at other parts. If you run into animals like the deathclaw or the Mao Guo (sp) thing you're probably better off taking out a leg or two first. They move really fast, hit hard and take a beating before they go down so you probably wont have enough VATS to kill them before they get to you. Take out the legs and you can backpedal, reload (drop mines) and wait for VATS to recharge while they limp towards you.
Also, if you're out in the open and the bad guy is using a rocket launcher or some other BFG I usually go for the weapon first then run up to them and use the shotgun on their heads while they scramble to find another weapon. And if you hit VATS and notice the guy is holding a grenade, shoot it.
I also tried to avoid the spoilers but also broke down and checked the bobblehead locations.
Unfortunately, I'm starting to see the glitches that are in the game too. I had the water plant NPC die on me (I'm guessing from radiation since I found him lying peacefully next to the bomb in Megaton) so now I can't sell scrap metal anymore. Also, I had a huge quest chain glitch on me at Jefferson Memorial. I did a bunch of quests only to have some people not follow me when they were supposed to. I probably spent more than an hour loading and re-loading and trying different things before I went to the boards to find out that a lot of the quests for that chain are broken and often can't be fixed.