Depending on the extent of the customization, Adobe Premiere may not be the ideal program for creating custom titles. If the customization only goes as far as changing font, or text color, or adding outlines, Premiere’s “Title” window can handle the job just fine. For creating custom graphics however, it would be better to use programs like Adobe Illustrator or Photoshop. Keep in mind that a custom title created in one of these programs would be imported into Premiere as an image and not as a title.
For a tutorial on working with Photoshop in tandem with Premiere, click the Lynda playlist below.
Lynda Playlist: DLL Adobe Premiere Titles, Credits, Etc.