Basic T_codes:

SCC9 - Remote client copy
SCC8- - client export
SCC7 - client import
SCC5 - Client delete
SCC4 - Client create/client settings
SCC3 - Client log
SCC1 - Client copy through TR
SU01 - User create/modify/change password/lock/unlock
SU10 - Mass User create
PFCG - Role create
SU21 - Authorization object create
SU53 - Missing authorization find
SUIM - SAP User Information System (It summarizes many different SAP authorization aspects)
STMS - SAP Transport Management System
SE01 - Transport Organiser (Create/Modify/View logs/Display/Release TR)
SE09 - Transport Organiser (Workbench TR transaction)
SE10 - Transport Organiser (Customizing TR display transaction)
SE06 - System Change Option (Global setting/Client setting/Software Component Setting)
SE61 - Document Maintenance initial screen (SAP GUI logon text)
RZ10 - Edit Profiles (static change, restart SAP System)
RZ11 - Maintain profile parameters (display/dynamic modify)
RZ04 - CCMS: Maintain operation modes and instances
RZ03 - Maintain operation modes (Application Server Overview and operation mode distribution)
SM63 - Display/Maintain Operating Mode Sets
SCOTT - Email configuration
SOST - Email Analysis
SP01 - output controller: Spool request selection screen (All users data)
SP02 - output controller (List of Spool Request by any single user)
SPAD - Spool Administration: Output Device (Configuration)
SM59 - RFC destination create
SM58 - Transactional RFC
SMQ1 - qRFC monitor (Outbound queue)
SMQ2 - qRFC monitor (Inbound queue)
SPAM - Support Package Manager
SAINT - Add-On Installation Tool
SMW0 - SAP Web Repository:Initial Screen
SE38 - ABAP Editor: Initial screen (program/report execute)
SE37 - Function Module: Initial screen
SE16 - Data Browser: Initial screen (table level check)
SE11 - ABAP Dictionary: Initial screen (create/change and display table entries and structures/views)
SM30 - Call View Maintenance (Add data to a database table within your SAP system manually)
SNOTE - Note Assistant

Daily Monitor System Health Check T_codes:

SICK - SAP Initial Inconsistency Check
SM04 - User List
SM51 - SAP Servers Overview (Associated on one host)
SM50 - Process overview
SM66 - Global Work Process Overview
SM12 - Select Lock Entry list
SM13 - Update Requests: Initial Screen
SM21 - System Log
ST22 - ABAP Runtime Error
ST03 - Workload Monitor
ST04 - Performance Overview
ST02 - Tune Buffer summary
DB54 - Change View "Logical Systems":Overview
SMLG - CCMS: Maintain Logon Groups
SMGW - Gateway Monitor
SMMS - Message Server Monitor
AL11 - Display SAP Directories
SICF - Maintain Service
SMICM - ICM Monitor
SLICENSE- SAP License Administration
AISUSER  - SAP Support Portal User Maintenance Assignments

Database Related T_codes:

DB01 - Database Lock Overview
DB02 - Space Overview
DB12 - Backup Logs: Overview for Database
DB13 - DBA Planning Calendar

SM01 - Transaction code: Lock/Unlock
SM02 - System Messages
ST01 - System Trace