Plant where it's needed

Some people have had success just by eyeing up the bare spots in their towns and adding some trees. This is an ideal place to start because you might be closer to perfection than you realize. Remember to check in with Town Hall after each change or addition.

Town Gridding:

Each town is divided up into a 4 x 4 grid with each grid being 16 x 16 squares long and wide. A square is the same size as one pattern. The best way to begin would be to start with a full 16 x 16 grid, usually in the upper right (east) or upper left (west) section of town. Start laying down a pattern every step for 16 straight steps, then move down and repeat for 16 more. Do this until you complete your first 16 x 16 grid. Repeat for the rest of your town.

You must also take into account that the river will break "acres".

Eventually, you will end up with a grid pattern looking similar to this:
(This is not the actual size of the grid, only an example)

= Pattern

Now all that's required is to have between 10 to 14 trees in each "acre" along with at least 3 flowers.

Method

For a “perfect” town rating, at least 8 of the 16 acres must have the following (“perfect” level):

Requirements
0 trees and 27 or more flowers
1 tree and 25 or more flowers
2 trees and 23 or more flowers
3 trees and 21 or more flowers
4 trees and 19 or more flowers
5 trees and 17 or more flowers
6 trees and 15 or more flowers
7 trees and 13 or more flowers
8 trees and 11 or more flowers
9 trees and 9 or more flowers
10 trees and 7 or more flowers
11 trees and 5 or more flowers
12 trees and 3 or more flowers
13 trees and 3 or more flowers
14 trees and 3 or more flowers
15 trees and 3 or more flowers
16 trees and 5 or more flowers
17 trees and 7 or more flowers
18 trees and 9 or more flowers
19 trees and 11 or more flowers
20 trees and 13 or more flowers
21 trees and 15 or more flowers

The other acres must have the following (“decent” level):

Requirements
0 trees and at least 21 flowers
1 tree and at least 19 flowers
2 trees and at least 17 flowers
3 trees and at least 15 flowers
4 trees and at least 13 flowers
5 trees and at least 11 flowers
6 trees and at least 9 flowers
7 trees and at least 7 flowers
8 trees and at least 5 flowers
9 trees and at least 3 flowers
10 trees and 0 or more flowers
11 trees and 0 or more flowers
12 trees and 0 or more flowers
13 trees and 0 or more flowers
14 trees and 0 or more flowers
15 trees and 0 or more flowers
16 trees and 0 or more flowers
17 trees and 0 or more flowers
18 trees and at least 3 flowers
19 trees and at least 5 flowers
20 trees and at least 7 flowerss
21 trees and at least 9 flowers

Do not leave trash on or buried in the ground. Do not allow more than 2 items (other than fruit, acorns or shells) on the ground in each acre. Do not allow more than 2 weeds in each acre. Remember to water your wilting/withering flowers so they won’t disappear.

Notes:

At some point you might lose your perfect status even though you didn't touch a thing. Many people have reported this and it's easily fixed. All that you need to do is add a tree to a low count "acre" or in another bare spot. You could also try adding some more flowers to each "acre". As long as you get back to perfect status before the 6:00am town reset, you will be fine and will not have to start your count over. You also might get into a rut where each time that you plant a tree you are told that there's too many trees. And when you remove that tree, you are told to add more green or trees. The simple solution is to start chopping trees down. After each tree, check in with Town Hall to see if it made a difference. This is a balance issue where you have reached the max count of trees in some areas and don't have enough in others. This can be avoided altogether by using the gridding method posted above.

Good Luck!