1. Clear understanding of requirement.
2. Construct the how-to before actual coding starts.
3. Avoid using multiple read to the same database table.
4. Make sure to use indexed field while reading to database table.

1. Don't use the followings :-
  a. loop within loop.
  b. select endselct.
  c. Occur (statements)
  d. Move corresponding.
  e. use of cluster tables.
  f. use select * (all feilds)
  g. use of OR statement in select statement.
  h. use of negative conditions.
     
2. Use the following :-
  a. loop with reads if needed to be read multiple time.
  b. Use of IN statement in select statement instead of OR.
  c. use of maxium key feilds with select statement.
  d. use of function modules instead of select statement 
     if it is available.

Additional to above points,

In select query Use For All Entries while pulling data from 
database.

Frequently don't use inner join in your program

While Looping create work area and process the record

These are some points to improve performance of program