It doesn't matter if you rely on your own mine production or if you steal the resources from other players, those will almost never be the exact amount you need for construction or research. Here comes the possibility to trade your resources, for example to compensate your lack of metal with your deuterium surplus. You can do that by trading with other players or by using the trader.
The classic trade
When doing a trade with players, both of the trade partners send a predetermined amount of resources to the other player. Because of that, not only the amount of resources but also the coordinates to which they are to be sent should be arranged. An arrangement according to the delivery time is advisable also, so that the trading fleet does not arrive in the middle of the night and the resources do not lie around unprotected for hours.
Basically trading must comply with the rules. Resources should only be traded in such a ratio, where nobody would benefit exceedingly (at which only an advantage of the stronger player will result in consequences). Normally the ratio of metal, crystal and deuterium is between 3:2:1 (that means e.g. 300 metal to 100 deuterium) and 2:1:1 (e.g. 100 deuterium to 100 crystal). Furthermore a trade must be finished within 48 hours; otherwise the responsible game operator must be informed about the delay using the ticket system (see Ticket system guide). In other respects both trade partners will be banned because of pushing, if the rule is broken, that means a stronger player profits by a one-way trade.
Where do I find trading partners?
Asking your own alliance or friendly players is the best and the most secure method. They often give you a better ratio than foreign players and the danger of getting ripped off decreases, because basically you cannot cheat a trade partner.
If you are not a member of an alliance or if there is nobody who has the resource you are looking for on sale, the board will be a good place to trade. In the forum OGame.us Board - The Universes and there in the sub-forum of your universe, in the trade forum, you can open a new thread and present your offer. There you should specify the amount and type of the wanted and demanded resources, as well as the ratio and the galaxy, in which the trade shall take place. Potential buyers will contact you in the thread or in-game, if you give out your contact information. You can also respond to the offers of other users, but please check if they already traded or not by checking whether they asked to have the thread closed or not. Please also note the trade rules, they are stickied deliberately and they should be closely paid attention to.
The last alternative is the IRC-network. In the channel of your universe you will find some active players for sure, who you can ask for a trade. You should however not be too pushy and end up annoying the others – if you bother other users, superior fleets will call on you fast, instead of trading partners. If you are permanently looking for resources, for example deuterium, you will be able to integrate it in your nick on IRC or also in the game (e.g. Alex[Deut]), and hope for potential buyers. See the IRC guide.
How do I use the trader?
If there is no human trade partner or if nobody has the wanted resource on sale, you will be able to use the trader, who you will find in the main menu under “trader”. There you can call a trader, who trades with a certain resource, by clicking on the according button (Of the resource you want to sell). Calling the trader costs 3.500 DM, which will be specified in the chapter Premium features. You can also find traders on Expeditions, however those only buy a certain resource, which is possibly not the one you want to dispose of at that moment. If you find a trader while another trader is already active, the located trader will buy the same resource as the present one, only the ratio will change.
If you have decided to use the trader, the window on which you can trade the resources, will appear. There you can see the ratio for the first time, this is assigned coincidentally, but it is mostly under 3:2:1. If you are not pleased with this ratio, you will be able to call a new trader; doing that will make the old one disappear – you spend another 3.500 DM. If you are pleased with this ratio, the trade can begin. Because the trader will stay until you either use it or call a new one, you can take your time.
For example, if you call a trader, who buys deuterium, you will be able to specify the amount of metal and crystal you want to buy. You can ask for as many resources for as much deuterium you have, and as the according storage can take. Definitely it will be profitable to upgrade the storages before trading, because every trade event costs the same, regardless of the amount. Because of that, a trade should be done on a planet, because there are larger storages which makes sense compared to a moon, where storages aren't necessary.
After you have entered your desired amounts of resources, you only have to click on the button “Trade resources!” to confirm the trading event. After that, you get the desired resources, and the trader will receive the exchanged resources and disappear.