Some conversations, and ultimately some quests, are made easier by having a high barter. See, this game goes by the old style of speech challenges, in that it's not a randomly determined stat based on your speech and charisma, but rather whether you fail or succeed is based off of how high a certain stat is. For example, I think one early quest has you ask a merchant for help as an optional part of it. If you don't have the 25 barter necessary, you fail the speech challenge and don't get his assistance, so it does pay to put a few points here and there.
That being said there are magazines that temporarily increase your skill in a particular area, such as bartering, for a very short period of time. They are 1 time use though, and when I say short I mean REALLY short, so use with caution.
Honestly, I think the biggest thing you can prepare yourself for in this game is the bugs, because going into it with a good mind set can definitely ease the frustration. Slowdown, stoppage, and random freezing occur more frequently the more you play, with some areas being almost completely unplayable to the point of powerpoint presentation if you've been playing for a long period of time. Going into this game realizing that freezing and slowdown are major issues will help in the long run, my patience ultimately worn too thin after the 15th time it happened to me and I returned it, but I do regret it simply because the game had an amazing story.
Gameplay wise... same old Fallout stuff. Collect everything, sell everything, help people for benefits or just murder and pillage everything they own. One thing I found somewhat frustrating was the lack of house really early on, but I guess you can use one of the houses in the starting town without being explicitly told that you can, but otherwise its a great game with a great story.
Hmm... one last bit. I'd stay away from energy weapons, they are really underpowered in this game and eat through ammo like it's no one's business. I've heard making your own ammo for guns is the best way to get through the game, but I never bothered to try.