If you want to buy with fiat check https://www.ccedk.com/
Young but smooth exchange.
If you have either...
USD
EUR
GBP
SEK
NOK
DKK
CHF
then you can go from those currencies to Nxt in one step. It is new so you may find there aren't enough orders to get the amount you want. Just put your orders in and I'll drum up some people to sell to you
You can then hold them on the exchange and do nothing. Or create and account and move the NXT there. I am told you can do this here: http://www.secureae.com/ but I have never tried it myself (it is trustworthy in that Wesley, the main client developer, created the front end for the website so your password never leaves your comupter).
N.B you can also buy with BTC and LTC if you have it.