White Tendency = check

Fought Maiden Astraea = check

Encountered BF form of Garl Vinland = check

Defeating BF form of Garl Vinlan = Houston, we have a problem

There are two ways to do it nice and easy:

1 - Get yourself a large two handed sword, like Dragon Bone Smasher or Meat Cleaver. Position yourself in the circular like area in the western corridor, just before the "invisible wall" that Garl Vinland encounters that prevents him from going forward and just mash R2 smash attack, especially when he's recovering from his smash attack, you can lure him into doing it over and over again

2 - Equip yourself with the Firestorm magic spell, insanity catalyst or Wooden Catalyst, approach the same area as before and lure him into a smash attack. Once he's recovering from it, approach him fast and cast the spell. Don't try to do it if he's not recovering from the smash attack, as he'll block the grand % of the damage of Firestorm.

Other than those two tactics, almost every weapon can defeat him, granted that you have the patience to take small damaging pot-shots at his health while constantly luring him into his own smash attack.

Ok thanks.

As lestatdark said, the main goal is to lure him into attacking. This requires you to dodge, but once you dodge, he is open to melee attacks. There is the invisible wall that he will not go past, so just dance inside his range to get him to attack, dodge, then go on the offensive. It takes a while to kill him depending on the weapon you are using, but it is mainly an endurance battle rather than a difficult one.

Edit: Here is a video showing the general strategy. You can do it with just about any weapon as far as I know.

http://www.youtube.com/watch?v=Deki1BgL028

guess who's late to the party?? ME!!!! I'm late to the party!!!

I was doing pretty well, finished 1-1, 1-2, 2-1, 5-1 and died only once (got greedy in 1-1, tried to pick up all the treasures in the area with dragons and was smashed to death by the tail )

then I tried 2-2 and the flamelurker totally ravaged my sorry ass >_<

what should I do now???!!! the enemies in 4-1 looked so brutal so I went with 3-1 instead and the first enemy zapped half of my health with one hit, WTF!!!

Curses,I still haven't got this game yet.

You should preserve on 4-1. Since you've already done 1-2, you can try killing the Red Dragon (if you got a good bow, over 16 agility and a couple hundred arrows), by positioning yourself at the top of the first tower on the dragon's path and taking pot-shots at his health. It should take at least 10 minutes to kill him.

It will be worth it though, since then you can go back to 1-1 where the red dragon was roosted, and pick up a Purple Flame Shield. This is the second best shield in the game, in terms of Guard Reduction and 100% Damage Reduction, if you level it up all the way to plus 10. 

With this shield, it should be a cakewalk to block the skeleton's attacks from 4-1 (except the Black Skeleton attacks, that one you should dodge like mad). 

World 4 is the best world to farm for souls early in the game, so you can get a nifty SL boost in it, that will allow you to tackle world 3 in a much easier fashion. Also, the bosses in world 4 are amongst the easiest in the game, so you can finish it quite fast. 

If you're still having trouble in world 4, you could ponder trying to complete World 5 first instead. This is because the boss in 5-3 drops an amazing shield which has 100% Magical Damage Reduction, and it's the best shield for this effect.

I already killed the red dragon and have the purple flame shield, just don't have enough strength to use it yet, what should I do with the red dragon's soul? can I just consume it or should I keep it with other demon's souls?? I think I'll give 4-1 a try tomorrow.

Consume it, since it isn't used for any kind of special forging, unlike all other demon's souls. You should do the same when you kill the Blue Dragon.

Try to get at least those 22 Strength needed to equip it then, I recommend that shield for almost any kind of build due to it's usefulness.

lol I only have 15 strength....gonna take a while before I can use my shield, I think I'll go through 1-1 a few more times before attempting 4-1 because I don't have any souls and wasted most of my weeds on flamelurker.