Good roleplaying skills are essential. No Genius Gnomish gal wants a giant bore. Regale her with tales of your future cross-continental adventures:
"You and me, babe, we're gonna fly to Kalimdor, etch our names into the side of Teldrassil and spend the rest of our lives swinging from the trees in Un'goro Crater."
Share stores of your exciting future together! The more implausible, the better. Nothing gets a Gnomish girl excited like an ambitious plan. It also makes for great conversation starters!
"With our brilliant minds combined, we could retake Gnomeregan. ... why haven't we retaken Gnomeregan anyways?"
Teasing is the art of making fun of a woman in a humorous way. Be careful, you can easily go too far. Calling her a "Goblin Ganking Gnat" will leave you walking home wearing that Green Gordok Grog you just bought. Try something a bit more subtle.
If she acts childish and refuses to stop jumping onto tables in the middle of the bar try:
"I hear there's an opening for star entertainer at the Stormwind orphanage."
If she won't stop talking about herself playfully try:
"Where's your off switch?"
IMPORTANT NOTE: Gnomish girls do NOT have an off switch. Attempting to find it may result in the loss of life, limbs or wallet.