Can you give us an idea on what you want to spend or invest, are we talking a few dollars or a few hundred or thousand dollars??
The best advice that i have found is to purchase key dates and the better the grade the quicker the appreciation. Gold is also another oppertunity as the price fluctuates all the time there is a gain to be made if you have watched the market and buy at a low. I once purcahased a bunch of sovereign and half soverign coins from briton, I sold them 9 months later here in NZ and made a 150% markup.
Cheers Sasnz