Each Origin Story is unique, and each can add a different flavor to the way that you view the game. In many ways they each make this a different game, which is rather cool if you think about it. Before we begin there are some facets to the game that you should be aware of because knowing about them will save you some frustration and help your game play along.
Relationships: As you add party members, you begin to develop relationships with each. Some of the characters you will identify with, like, and trust, while others you will not. Depending upon how you play the game, some will end up being part of your active party more often than others, but even if you only add one to your group and never actively use it in party play, you should make the effort to both develop your relationship with them, and maintain it.
At various points in the game you are going to be asked to make decisions of a moral nature that not only impact the path you follow in the story, but also have a direct effect on some of your party members. If you have played RPG games in the past, you know about alignment - if you have not, alignment is a basic identification of the moral outlook for a character. They can be good, evil, or neutral, but their alignment directly effects what they think of you when you make these pivotal decisions.
If certain characters are important to you, you will have to take that into consideration when you make decisions - for example you may want to kill someone in the game very badly, but if you do, it could force you to have to kill one of your party members! While you cannot always keep everyone happy all the time, there is usually a way to keep from having to kill them.
Throughout the game you will have the opportunity to loot and purchase items that are tagged as "Gifts" that can be given to your party members to increase their positive feelings towards you. Some gifts are general and can be given to anyone, and result in a 1 or 2 point raise, while other gifts are exclusive to a specific party member. If you give that gift to the wrong person, you only get the usual 1 or 2 point raise, but if you give it to the correct person, the raise can be anywhere from 5 to 10 points! Consult the Gift List in the Appendixes to determine who to give what.
In addition to showing approval for your moral decisions, the amount that a party member likes you is also important if you want to earn the Achievements / Trophies for romancing them. This does not apply to all of the party members, just to Alistair, Leliana, Morrigan, and Zeveran. The details and requirements for romancing each is noted in their dossier. Be aware that if you are romantically involved with one, the others will be aware of it, even if you never make them active as a party member!
There are certain items in the game that are part of quests. These usually appear in the Plot Items heading in your inventory, but not always. Great care should be taken in disposing of items that are quest related, since losing or selling them can make it so that you can no longer complete a given quest. To learn what items you need to hold on to and in what quantities, see the Quest Items List in the Appendixes before you continue on to learn what you need to hold on to.
Finally, there is the issue of inventory. At the start of the game you have a backpack that only holds a certain number of items. Items that stack only count as one item, but as you play and loot you will quickly discover how easy it is to end up full! Certain merchants that you meet in the game have backpacks that they can sell you that will add 10 slots to your inventory - always check a merchant to see if they sell this, and always buy it if they do.
Now that you have completed your Origin Story, it is time to begin the story line of the game, so good on ya mate! Let's get adventuring!