If I had to give one tip it's that you can't die, so focus on charisma and wisdom early for dialogue. That's how you get the best experience of the game. You can always grind XP from thieves if you find early fights difficult.
Second is to always pay attention to what you're told. Non-spoiler, you open the game surrounded by zombies that are actually neutral. Your first instinct might be to say "sweet, I can get ahead of the XP curve!", but PS:T isn't that kind of game. Further, dialogue isn't just an exercise in exhausting all the possibilities, be tactful when you speak. Having said that, Fallout has prepared you well for this, but you may find this game takes it a step further.
Last thing: Lower speed ratings on weapons are better. It's just a little thing that had me confused at first. Fist weapons and daggers are great weapons for warriors (which you are bound to be for most of the game, since you only get to dual-class after many hours) and will get you through the game just fine.
Also, I believe on the store page on GOG there's a list of recommended mods that are all pretty much straight upgrades, so look through that.