You could use the following methods (from Database Backups in the documentation)
Making Backups by Copying Files
MyISAM tables are stored as files, so it is easy to do a backup by copying files. To get a consistent backup, do a LOCK TABLES on the relevant tables, followed by FLUSH TABLES for the tables. You need only a read lock; this allows other clients to continue to query the tables while you are making a copy of the files in the database directory. The FLUSH TABLES statement is needed to ensure that the all active index pages are written to disk before you start the backup.
FLUSH TABLES WITH READ LOCK;
Closes all open tables and locks all tables for all databases with a read lock until you explicitly release the lock by executing UNLOCK TABLES. This is very convenient way to get backups if you have a file system such as Veritas that can take snapshots in time.
UNLOCK TABLES;
Making Delimited-Text File Backups
To create a text file containing a table's data, you can use:
SELECT * INTO OUTFILE 'file_name' FROM tbl_name
This method works for any kind of data file, but saves only table data, not the table structure.
To reload the output file, use"
LOAD DATA INFILE