Rules to follow.

• Every bird in the pedigree must be entered.
• Each bird is only entered once.
• Parent birds should always be entered before their children.

Have a procedure in mind.
Here is mine.
First identify any bird that is entered in the pedigree more than one time.
The gota for data entry is when a bird is in the pedigree in more than one generation.  Choose to enter the earliest generation ( first pedigree position) the one with the  most ancestors  listed, and mark the others entries and done.  This allows you to use the picklist feature for pulling down parents rather than manually entering them.  This is a key to not messing up the database.  The system of numbering use in the long pedigree will always have the first occurrence with the lowest position number. 
Using this rule below I find the first occurrence of 0700 and its parents is in position 2 of the pedigree.  I then mark the second occurrence as done!  If you have a hand written pedigree you may have to decide which set of parents if correct for a bird.  I often find a different year or sevens confused with 4s.  This program will not allow different parents for the same bird.

Rules I follow.
Set you mental mode to changing the birds status to [ I ] or inactive.
Set your mental entry mode to enter the birds without parents.
Start with the bird with the highest position number, and work downward by position number for birds without parents
9 - 9974 TC AU98
8 - 1645 TC AU94
7 - 5090 TC AU98
5 - 0100 TC AU95
Change your entry mode to birds with parents.
Start again with the bird with the highest position number and word downward by position number.  Often use the screen pedigree [ DETAILS F2 ] to review your progress.
4 - 0700 TC AU99
3 - 1104 TC AU01
2 - 1208 TC AU02
1 - 1456 TC AU03
When you have completed and are about the end be sure the new bird is marked as active.

The specific procedure isn't as important as having a procedure in mind before you start; and that you do the parents first.