Just want to add that the aroma can be diminished significantly if the wine is served too cold.
If the wine is at or near room temperature and the aroma is still weak, then there are a few possibilities:
1) Decant, or let the wine sit in your glass for 10 or 15 minutes--air contact often opens up the bouquet.
2) Bottle age. If you can sense the aromas you want in the bouquet but they are just too faint, bottle age should intensify the aromas, as well as produce more complexity.
3) The fruit or winemaking techniques just didn't result in an aromatic wine. It happens--sometimes by fluke and sometimes you can predict it (ie a cool fermentation for whites increases floral and citrus smells).
4) Oak age. For whites, it can take away much of the floral and citrus notes and replace them with more austere vanilla and smoky scents instead. For reds, this is often desirable but rarely for whites (of course oaked Chard or Sauv. Bl would be exceptions here).
If you fermented cool, aged with no oak, bulk-aged then bottle-aged at least a couple of years, served the wine at room temp., and let it get some air in the glass or decanter, and it still has very little aroma, then I would look to the ingredients you used...generally it is preferable to get the most out of the wine you are trying to make rather than "artificially" augmenting the bouquet or flavours by adding other materials...