To adopt an orphaned package it's easier than you think! adopt now :3
What you need to do is register, find an orphaned package, then click on the "Adopt Package" link.
Don't forget to set your public key on your "My Account" menu.
After that you can clone the repository, see "Git Clone URL" on the first line of the package, edit and reupload:
# do some changes on PKGBUILD
git add .
git commit -m 'updated bla package to version X'
git push origin master
Done :3 you have successfully adopt and maintain a package :3