00 : Formulate your strategy. This is perhaps the most important tip of all. Before you go in, spend some time researching your options. There are dozens of figure lines out there, find one (or more...) that fits with your criteria regarding assortment, quality and price. Consider if you are going to focus on particular mobile suits from various figure lines, or spending time to get many types in a series instead. Are you going to focus on a particular Gundam time period, or a particular faction? Are you looking for advanced details, moving parts or something handy? Setting this goal early will make it easier for you to trawl through the thousands of Gundam related items available online.
01 : Grab it while it's hot. One obvious feature of the miniature figures is that they are usually released in waves over time. As a consequence most models would quickly disappear from the market and end up on the second hand and collectible arena, now with very different price tags attached to them. Although some figures in the Ultimate Operation and Converge series have shown up in re-packs (these often differ in some slight aspect, such as colour tone), the overwhelming majority quickly came, conquered the shops and then left. If you have the opportunity it is often a good idea to pick items up while they are still fresh in the shops.
A normal STANDart wave contains four different models, but they are sold in boxes containing six figures. Assault Kingdom figures (four per wave) come in boxes of ten, as do Converge items (which are six plus one secret figure per wave). Make sure that you know if you are purchasing a hand-picked set or a random box. And if you are purchasing a Converge set, make sure you know if the secret seventh item is included in the set or not.
04 : Know the market. Before jumping into the fray, take some time to look around what is available to try to get at least a rudimentary feel for the going rates for the different waves of figures. Older figures will quickly rise in price, a fate that also befalls popular models from recent waves. Unless you are looking for some really old models there should be a fairly decent supply of the later waves, so start your bargain hunting there. This will give you a better idea of availability and pricing, which will aid in your purchase decisions for more expensive and long out of production figures.
06 : Stay up to date. Many blogs and shops repost information from the manufacturers, but it is just as convenient to go to the source and keep an eye on the Bandai shokguan page directly. Here you can keep track of new releases in the still running product lines.