What can I tune to get things improved?

 >>  MySQLTuner 1.2.0 - Major Hayden <major@mhtx.net>

-------- General Statistics --------------------------------------------------
[--] Skipped version check for MySQLTuner script
[OK] Currently running supported MySQL version 5.0.95-log
[OK] Operating on 64-bit architecture

-------- Storage Engine Statistics -------------------------------------------
[--] Status: -Archive +BDB -Federated +InnoDB -ISAM -NDBCluster 
[--] Data in MyISAM tables: 17G (Tables: 1421)
[--] Data in InnoDB tables: 33M (Tables: 1907)
[--] Data in MEMORY tables: 2M (Tables: 6)
[!!] BDB is enabled but isn't being used
[!!] Total fragmented tables: 113

-------- Performance Metrics -------------------------------------------------
[--] Up for: 17d 5h 8m 41s (146M q [98.768 qps], 6M conn, TX: 4896B, RX: 58B)
[--] Reads / Writes: 60% / 40%
[--] Total buffers: 666.0M global + 16.4M per thread (750 max threads)
[!!] Maximum possible memory usage: 12.6G (162% of installed RAM)
[OK] Slow queries: 0% (4K/146M)
[!!] Highest connection usage: 100%  (751/750)
[OK] Key buffer size / total MyISAM indexes: 512.0M/4.4G
[OK] Key buffer hit rate: 100.0% (19B cached / 5M reads)
[OK] Query cache efficiency: 72.5% (74M cached / 102M selects)
[!!] Query cache prunes per day: 109463
[OK] Sorts requiring temporary tables: 0% (31K temp sorts / 4M sorts)
[!!] Joins performed without indexes: 97125
[OK] Temporary tables created on disk: 4% (131K on disk / 3M total)
[OK] Thread cache hit rate: 93% (439K created / 6M connections)
[OK] Table cache hit rate: 43% (6K open / 14K opened)
[OK] Open file limit used: 7% (5K/65K)
[OK] Table locks acquired immediately: 97% (82M immediate / 84M locks)
[!!] InnoDB data size / buffer pool: 33.1M/8.0M

-------- Recommendations -----------------------------------------------------
General recommendations:
    Add skip-bdb to MySQL configuration to disable BDB
    Run OPTIMIZE TABLE to defragment tables for better performance
    Reduce your overall MySQL memory footprint for system stability
    Enable the slow query log to troubleshoot bad queries
    Adjust your join queries to always utilize indexes
Variables to adjust:
  *** MySQL's maximum memory usage is dangerously high ***
  *** Add RAM before increasing MySQL buffer variables ***
    max_connections (> 750)
    query_cache_size (> 128M)
    join_buffer_size (> 128.0K, or always use indexes with joins)
    innodb_buffer_pool_size (>= 33M)
Thanks for your help!