1. Follow the naming standards (of the company or client you are working)
2. Use select field one field two etc do not use select *
3. Avoid unnecessary loops. If requirec use loop with where clause or Read
with binary search
4. Use case statement in place of if else
5. use clear table before select single or where ever applicable.
6. check for sy-subrc where ever applicable
7. avoid collect statement if possinble
8. do proper documentation of the program inside abap editor and also
in se38 (screen-documentation radio button )
9. try to use views rather than nested select statement
10. use ABAP TRACE try to work on those SQL statements to improve
performance
11. use index only if it is required
12. in internal table declaration try to use correct occurs number say
occurs 1000. Otherwise use occurs 0.
13. while using select statements use single select, select * upto 5
rows ,etc based on the requirement.use select options wisely taking
performance into account.
14. declare variables / parameters with meaningful words like v_matnr for
material number or v_bukrs for plant or at least v_matnum for material
number etc.