Well, buying armours is indeed a bit of a waste of souls, even if you started as a Deprived (as I did), because the armour you eventually find in the game is better most of the times. Only in the late game will you find actually good armour in the vendors, so keep your souls. 

Bow and Arrows are definitely something you should look at. Even if you're not a Dex character, using a Bow is a good method of kiting and luring enemies individually instead of having to deal with crowds of them, which is particulary useful in some scenarios, like the Elite Knights at the entrance of the Undead Parish. Also, you'll want to buy at least 50 arrows (100 if you can afford it) and use them later when you go under a bridge to escape from a fire-breathing red dragon, since you can target it's tail to get an amazing weapon.

Repair box is also a good buy, but a bit too steep at the moment, and you can get it cheaper on a blacksmith located just a little further from the Undead Burg. If you didn't start with the Master Key gift, then the Residence Key is a must buy. It will open some doors in the burg, especially on the lower Burg (later on) in which you can rescue a NPC. 

So my best tip is to go for the Bow and Arrows first and then the Key if you can afford it. You can always come back after progressing a bit more in the game and have more souls, or you can farm from the Undead Soldiers nearby (1000 souls shouldn't take too long to get).

Princess Guard works similarly to Way of the White. There are no particular summon or invasion events in the covenant, but being part of either of those two covenants makes it much easier to find White Summon signs from other players in the same covenants. 

Also, Princess Guard allows you to use two miracles that are dropped from some of the medusa-like enemies on the prison in Dukes Archives, which are Bountiful Sunlight and Soothing Sunlight. Both are AOE healing spells, which work very nicely when pairing up for bosses. Those miracles don't work if you're not part of the Princess Guard.

@Xen - I hope I can be of assistance any time you require it Trust me, Dark Souls has as many, if not more, wonderful experiences as in Demon's Souls. You did well in getting it!

there are a few healing miracle's you can only use when in princess guard, also, You find helpful soulsigns easier from players of the same covenant.

@Xen: I feel almost sorry for you (Thats why i prefer to buy games in Stores like Gamestop - of course they are more pricey*, but you have them on Launch day.)

Have fun ^_^!

* Actually, i payed less for DS at gamestop than i would have on Amazon. rare occurence, but yeah, it happens sometimes.

HOLY MOTHER OF F**K O_________________o!

Something amazing happened, Anor Londo turned totally Dark, and all the enemys are replaced by NPC's WTF! ^_^

(What a single arrow can change.. lmao. ^^)

You bastard, how dare you do that to the big boo...I mean, sun princess XD. 

Those NPC's are amazing for soul farming. Just run from the chamber of the princess bonfire, kill them, cast homeward, rinse and repeat

which is why the Binoculars are the best gift in the game? :P

.. seriously, i was like 'wtf' xD.. its amazing that something like that can happen. o:

You get something useful out of that ?, her soul or something ?

absolutely nothing.

xD

Bastard !!

:p

she deserved it, teasing me  with the great sight onto her boobies, while they'd stay forever untouched.

and Ana.. Anor Londo at night has something special to it. :p