I decide where to put my digits by trying to have a total of 800 or 900 in the first column if it is possible to do so. If it is not possible then you must have the smallest numbers in the hundred's column and the biggest numbers in the one's column. Here is an example of my strategy if it is not possible to have 800 or 900 in the hundred's column.
If it is possible to make 900 or 800 in the hundred's column then you can have around 90 in the ten's column and around 10 in the one's column. Try and work around this trick if it is not possible because you might not get good enough numbers to use this trick. The closest I got was 1002 which was only 2 away. To sum it all up you want to have 100 or 200 less in the hundred's column 10 or 20 away in the ten's column and the rest go in the one’s column. An example was when i had hard numbers but made 800 first in the hundred's column 100 in the ten's column and the rest-which was 13-I put in the one's column which made 1013-13 away.