It is odd to me how OpenOffice Writer does the default outline. When I start to do an outline, I, like I'm sure many people do, prefer to have something like I., A., 1., a., i. However, OpenOffice Writer's autoformating gives me something more like the below… not what I want. Fortunately, this isn't too much of a hassle to change.

1. Highlight the outline that you have already started. Right click and select Numbering/Bullets.

2. In the new window, go to the Options tab.
3. In this tab you can custom configure an outline how you prefer it. The Level on the very left can be matched to the graphic on the right to find what level you are messing with. Numbering represents the actual style, such as I, II, III or 1, 2, 3. You can also fine tune a few other options as well, if necessary. Then click OK.

Once you finish, you have configured your outline for that document. To be able to reuse this, first create a very simple outline (you can just leave an "I" if you prefer). Then follow the steps below.
1. Go to File>Templates>Save
2. Choose the folder and template name you want and press OK.

Now whenever you go to File>New>Templates and Documents, then you can find your outline format ready to go.

(The latter howto in this article uses information from OpenOffice.org Writer Documentation.)