there's a good guide here BUT there are some things worth noting
http://www.mmo-champion.com/index.php?topic=38837.01)
Don't go to the classic dungeons to look for the bouquet of red roses... they don't drop any more, you need to do the Northrend instances
* Maiden of Grief (Halls of Stone)
* Prince Keleseth (Utgarde Keep)
* Prince Taldaram (Ahn'kahet: The Old Kingdom)
2)
You CANNOT use the bouquet of ebon roses for the other achievements (fistful of love or the flirt with disaster)
3) Carry Cologne AND perfume... some places (Thunderbluff) seem to be rife with cows and no bulls.
4) when you mend someone's heard, Make sure you remove your Friendship buff and you can keep chain mending people, otherwise you need to wait 1 hr for the achievements
5) Guards give the PLEDGES of Adoration, Non guards give the Gifts... you need the Gifts for the achievement
6)
you DO need to be inside Naxx to pity the fool there, same for other areas, don't believe people who say you just need to be near the portal
Here's my advice if you have a few hours to kill... the bits underlined you can ignore if you prefer to just go for gifts every hour and then do something else inbetween, it can be a bit tedious.
a) Dalaran -> TB
b) buy loads of tokens and 2 bottles of perfume and 2 bottles of cologne from an innkeeper, use one of them
c) get GIFT from NON guard (i.e. not a bluffwatcher)
d) you're adored now, but go round giving tokens to people with hearts (if they are the wrong gender just spash cologne instead of perfume or vice versa)
e) keep doing it until you have 5 flowers, 5 pledges, and 5 cards, use each of them to get 3 new items
cards come from Bluffwatchers, flowers from non-guards and pledges from both
f) use the 3 new items to get a TB Giftg) if you're heartbroken you can't hand in gifts, yell for a mend and someone will help you
h) repeat d e & f until you have some mopre TB gifts... I'd recommend 4 in totali) fly to Org
j) hopefully you're no longer adored, so go get a gift (i.e. NOT from a grunt)
k) repeat d e & f until you have 4 org gifts (cards pledges and pies this time)l) look for a quest giver near the bank who sends you to UC with a letter
m) Zep to UC
n) repeat j & k until you have 1 gift of adoration
and 4 UC gifts (cards pledges and poetry) make sure you get 1 spare guardian's moldy card
o) hand in the org quest from part l)
p) a quest giver will call you and ask for a Guardian's moldy card... you should have this from n... hand in
q) next quest needs a bottle of cologne and perfume, you should have a spare of each on you or go to an innkeeper. Handin
r) go to apothecary quarters- handin... go back to bank - handin... go to magic quarter tailor - handin... get follow up
s) now to hand in the gifts... when you combine an UC TB & Org Gift you get a horde gift... hand this in to the "cupid" in the Royal Chamber near Varimathras. you have a choice of rewards for other achievements you NEED 10 handfuls of rose petals, at least 10 rockets, and 10 arrows, each gift will only give you 5 of each so hand in your 4 gifts and choose what you need most (i.e. what you didn't get from the gifts of adoration)
t) before you leave UC, drink a load of alochol until you're "completely smashed" apply more perfume if needed, find the cocroach vendor by the bank, and /kiss and then use some petals on him (I don't think the bouquet works... you need a handful of rose petals)
u) pick up another gift of adoration if your buff has gone and then fly to tarren Mill
v) run up to hand in ... don't forget to click the cauldron
there's a map here on the screenshots
http://www.wowhead.com/?quest=8984#.w) hearth to dalaran
x) now loiter around dalaran and you can use your petals on specific class/race combos... use the track function in achievements to make it easier.
y) also look for someone under a parasol... click the picnic hamper
and Shoot 10 people with silver shafted arrows, make sure they don't have non-combat pets with them before you do it!
now find a quiet, un-laggy place to fire off 10 rockets in 20 seconds
You've now completed
Nation of Adoration
Flirt with Disaster
Nearest and Dearest
Fistful of Love
Lonely?
Shafted!
The Rocket's Pink Glare
if you've been mending hearts too you should have done
Heartmender
if you have some chocolate boxes from the gifts the sweet tooth is pretty trivial
that just leaves
Be Mine: hopefully you've also got some bags of candies to create the love hearts... they have 10 charges, good luck, if not then keep trying for gifts of adoration every hour until you comlete it
My Love is Like a Red, Red Rose: go to the dungeons mentioned (HoS, UK, Old Kingdom) to get the ebon roses... UK normal would be the quickest
I Pitied the Fool: this is like a target dummy, and it doesn't need to be yours... when you see one in the relevant location just target it and type /pity
needs to be done in: Wintergrasp, Naxx, AB Blacksmith, Culling of Strat, Battle ring of Gurubashi Arena