How do you beat calo nard?

Just use hit and run tactics.

Depends on when/where you're talking about. If you're pwning him on Taris, then just chuck a mass of grenades and ignore Davik Kang. However, if you're on Korriban, Tatooine, or Kashyyyk, (do you fight him on Manaan?) it may be a bit more difficult--just use your pwnderful tactics. Grenades, the Force, blaster/lightsaber/sword, etc. Oh and energy/melee shield. Just act like you should.

CALO NORD on Taris is basically a no-no. He is too powerful and he can kill you very quickly (well he killed me quickly anyway), and also you are not really supposed to kill him as he ties in with the plot later on... Well sort of anyway. I fought him on Korriban and if I ever got too low on health I just ran back into the complex and healed. Went back out and then Calo Nord and his cronies were still on the same health. Just keep doing that and you should beat him.

To beat calo nord you attack him untill he is dead with your weapon/s.

Well you can't beat him on Taris but just keep hitting him and he will die when you face him by the ebon hawk.

If you're talking about on Taris, If you kill the guy who owns the Ebon Hawk, then a scene will show him threatening to blow you all up, but then the sith bomb the building and stuff falls on his head.

If you're talking about after Taris (sorry for the spoiler!), kill all of his thug companions, then equip fresh shields to all of your characters (people always forget their party members and end up dead!). Then if he's using his blaster, get back and throw grenades (do this at the start as well), then move in for the kill. Get his armour (it's strong and looks cool - it's different to his clothes that you see him in all the time, it's silver and black).

First, you need a lightsaber, if you have one. If you do then keep your distance but activate your energy shield, and then your lightsaber will knock his blaster bullets back and whenever you can throw any grenades you have (the most affective grenades are frags and ion grenades). And once his health gets to about 1/4 then just run up to him and use flurry a bunch of times until he dies.

You can defeat him by throwing 1 thermal 1 frag 1 poison 1 ion

I easily defeated Calo Nord on Tatooine by raising my characters level to 19. He was easily defeated by Force Kill.