Originally Posted by HillRider
I agree with the desirability of owning and using torque wrenches, particularly for the new bike mechanic. An experienced mechanic with years of working on a variety of bikes can get along fine with out one (e.g. Sheldon Brown) but the new guy has no idea how tight things should be or what the proper torque feels like. It is likely you will never get bottom bracket cups or crank fixing bolts tight enough and will probably over-tighten small bolts without one.
Bobby Lex's comment about the intolerance of very light and exotic components to improper torque is right on.
You don't need anything sophisticated like a "clicker" or electronic wrench. A plain "beam type" as shown above is fine for any bike work since you can always see the scale.
I agree completely with Hillrider. I'm also an instruction reader and feel you can't go wrong if you follow them. I use a torque wrench whenever I can. A common post on here is loose crank arms, which is remedied by proper torque on the crank arm bolts (around 30 to 35 ft-lb). I've seen some apply "gorilla" torque which is unnecessary, can damage or make disassembly that much harder.
You'll need sockets and hex-bit sockets (for Allen screws). You won't need many, but they're cheaper if you buy them in a set. I suggest higher quality tools, like Craftsman. They'll last you a lifetime. I've used poor quality tools, with loose tolerances that damaged fasteners.