Some usefull TIPS

USER idle time

SELECT sid, osuser, username, status,
TO_CHAR(logon_time, 'DAY HH24:MI:SS') LOGON_TIME,
FLOOR(last_call_et/3600)||':'||
FLOOR(MOD(last_call_et,3600)/60)||':'||
MOD(MOD(last_call_et,3600),60) IDLE, program
FROM v_$session
WHERE username IS NOT NULL
ORDER BY last_call_et;

USER temp tablespace

SELECT username, default_tablespace, temporary_tablespace
FROM dba_users
ORDER BY 1;

USER informations

SELECT u.username, u.default_tablespace, 
u.temporary_tablespace "TMP TBS", u.profile, r.granted_role,
r.admin_option, r.default_role
FROM sys.dba_users u, sys.dba_role_privs r
WHERE u.username = r.grantee (+)
GROUP BY u.username, u.default_tablespace,
u.temporary_tablespace, u.profile, r.granted_role,
r.admin_option, r.default_role;

Create user sample

CREATE USER username
IDENTIFIED BY password
DEFAULT TABLESPACE tablespacename
TEMPORARY SPACE temp_tablespacename
QUOTA UNLIMITED ON tablespacename; 

GRANT CONNECT TO username;
GRANT RESOURCE TO username;