Alright, lets try this actually in the right thread:
Whips are as strong as miniguns in this game, just because of how the game handles them.
If you see someone with a whip, kill it with ranged. Do NOT send melee in - they will die, even in full adamantine, in seconds.
Also... a few more tips...
Siege weapons are insanely useful when set up properly. Give them a long, straight, fairly narrow path to fire down.
Marksdwarves like to run up and hit things. Seal them in their fortification room so they can't.
If you embark in a hostile area, the first thing you should do is dig a trench around your wagon.
Lava burns. With that common knowledge in mind, do not flood your fortress with it. If you DO start to flood your fortress with magma / lava, shut off the magma/lava source. If that is not possible, counter-flood it with water if possible. It's far easier to pump out water than magma, and water destroys (slightly) less. Either way, it's going to be Fun.
For the previously mentioned reason, magma-proof doors are a good investment.
Be careful mining adamantine, as there is a certain
spoiler if you do it wrong. In fact, if you find adamant early, it's not a bad idea to just leave it sit until at least mid-game (usually 5 or 6 years in) when you have a strong military. If you do mine it, you should mine out around it, smooth the stone, then carve fortifications into it. If it is safe, mine those tiles that you carved. If it isn't, you have a nice set of fortifications between yourself and the spoiler.
Flowing water is bad for frame rates. So is flowing magma, but slightly less so.
Water + lava = fun. And obsidian. Mine this obsidian, because it's a great building material.
Use stockpiles liberally. If you don't, you'll find your craftdwarves spending more time gathering the needed materials than actually crafting.
Traps are good. Automatic traps (pressure plates) are even better, but be warned: Anything unconscious, including your own Dwarves, falling on a plate will trigger it.
Build towers near your entrance, even if your fortress is otherwise underground, to protect against flying mobs.
Flying building destroyers suck. Kill it quick. Preferably from behind fortifications. Usually, fire will not work, as they tend to be dragons.
All undead, to my knowledge, are building destroyers - but can only destroy wooden buildings.
Mega-beasts with toxic blood or "beware its (poisonous/toxic) [anything]" Should be killed by cave-ins, with your Dwarves nowhere near it. If it flies, you're screwed. Be creative, just don't get your Dwarves near them - it might not kill them right away (usually it will), but it may kill them after a few months.
It is a very bad sign when your Dwarves are giving off miasma while alive.