In general we follow Jeff Hunter [1].
However, scripts starting ASM databases are not
quite like as in [1] due to different ORACLE_HOME's directories for ASM instance and database utilizing ASM in case of 10g R2 version of server. In case script /etc/init.d/dbora doesn't export any ORACLE_HOME value.
It just runs script in ~oracle directory responsible for export right ORACLE_HOME value at right time

Installing Oracle10g Release 1 (10.1.0) on Linux - (RHEL 4) at
by Jeff Hunter