New functions should be developed against latest developement version ("trunk" lying at http://svn.osgeo.org/gdal/trunk/gdal).
Create a new Ticket of type: enhancement and now we refer to this ticket when submitting driver code, driver test cases, changes to the building configuration required for the new driver, etc. So, we can track all necessary updates and changes in one place, using a single Ticket. After a new driver is incorporated and well tested, we can annotate and close the ticket.
Contributions may also be proposed as pull requests against the git mirror hosted at https://github.com/OSGeo/gdal
Code contribution shall be done under the MIT/X license in order to be incorporated into GDAL/OGR baseline. Refer to the Legal paragraph of RFC3 for more details.
Subscribe to the mailing list and answer questions where you have gained some knowledge (and everybody knows something!).
Contribute to the wiki, improving documentation, providing examples, etc.
File quality bug reports in Trac when you observe errors. The greatest value comes from boiling down the problem to the minimum manifestation with small data files such that a developer/maintainer can very easily reproduce the error.