When a one-syllable word ends in a consonant preceded by one vowel,
double the final consonant before adding a suffix which begins with a vowel.
This is also called the 1-1-1 rule: one syllable, one consonant, one vowel!
Examples: bat--batted, --batting, --batter; prod--prodded, --prodding
Try spelling these:

1.

state + ing =

2.

like + able =

3.

indulge + ing =

Do not drop the "e"
when the suffix begins with a consonant:
Examples:  state--statement; like--likeness; use--useful; definite--definitely
Try spelling these:

4.

base + ment =

5.

home + ward =

6.

peace + ful =

When "y" is the last letter in a word and the "y" is preceded by a consonant,
change the "y" to "i" before adding any suffix except those beginning with "i"
Examples: beauty--beautiful; fry--fries; hurry--hurried; lady--ladies
Try spelling these:

7.

carry + ed =

8.

fancy + ful =

9.

pry + ed =

When a word ends with a "y" and is preceded by a vowel,
to form the plural of its noun,
or to form the third person singular (he, she, it) of its verb,
add "s"
Examples:  toy--toys; play--plays; monkey--monkeys

10.

deploy + s =

11.

 tray + s =

12.

 bey + s =

When a one-syllable word ends in a consonant preceded by one vowel,
double the final consonant before adding a suffix which begins with a vowel. 
This is also called the 1-1-1 rule: one syllable, one consonant, one vowel!
Examples: bat--batted, --batting, --batter;  prod--prodded, --prodding
Try spelling these:

13.

bid + ing =

14.

stop + ed =

15.

knit + er =

When a multi-syllable word ends in a consonant preceded by one vowel,
and the final syllable is accented,
the same rule holds true: double the final consonant.
This is a variation of the preceding rule
Examples: control--controlled; prefer--preferred;
begin--beginning; commit--committed
Try spelling these:

16.

patrol + ing =

17.

omit + ed =

18.

forget + able =

When the final syllable does not have the end-accent,
it is preferred, and in some cases required, that you NOT double the consonant.
(The preference characterizes American English; British English seems to prefer doubling, though it often allows its omission. But a number of words disallow doubling in both American and British English.)
Examples: focus--focused; pardon--pardoned;
worship--worshiped; trumpet--trumpeted
Try spelling these:

19.

garden + er =

20.

limit + ed =

21.

market + ing =

Adding suffixes to words ending -ce and -ge
Keep the silent e before -able and -ous
Examples; enforceable, serviceable, courageous, outrageous

22.

notice + able =

23.

courage + ous =

24.

change + able =

"ie" examples:  

fiery, friend, mischief, view, believe

"ie" examples: 

reign, foreign, weigh, neighbor, weird, receive