Some rules can be followed for regular endings for verbs and nouns.

Adding -ing and -ed to verbs

In English, verbs are often changed by adding -ed (past tense) or -ing (for a sense of continuous action). These are known as verb inflections.

When adding -ed or -ing to a verb ending in e, the first spelling rule to remember is to ‘drop the e’:

bake     baked     baking    

change     changed     changing   

The second spelling rule to remember is to ‘double the consonant’ when the verb ends with a single vowel and consonant:

pat     patted     patting

step     stepped     stepping

but 

peak     peaked [because there are 2 vowels before the end]

camp     camped [because there are 2 consonants at the end]

Exceptions to these rules

Verbs ending in -ee, -oe or -oo keep their 2 vowels before adding -ing or -ed:

agreeing/agreed     decreeing/decreed     canoeing/canoed     tattooing/tattooed

Verbs ending in -ge generally drop the e before -ing, but retain the e if the meaning would otherwise be confused, or in a few uncommon verbs:

arranging     changing     exchanging     impinging     staging
but
singeing [which would otherwise be confused with singing]

Some words can be spelled either way:

bingeing/binging     tingeing/tinging 

and a few always retain the e:

whingeing

Verbs ending in -l, -r, -s or -t

For verbs ending in -l, the l is doubled before the -ing or -ed, in line with the rule to double the consonant:

compel     compelling     compelled   

enrol     enrolling     enrolled

pedal     pedalling     pedalled

For verbs ending in -r, -s or -t, the letter is doubled when the word has 1 syllable, or has 2 syllables with the stress on the second:

Base word 1 syllable:
bar     barring     barred

scar     scarred     scarring

bus     bussing     bussed

bat     batted     batting

Stress on the second syllable:
defer     deferred     deferring

transfer     transferring     transferred

admit     admitted     admitting

regret     regretted     regretting

permit     permitted     permitting

But the t remains single if the stress is on the first syllable:

benefiting     budgeting     marketed     targeted   but   formatting

For 2-syllable verbs with the stress on the first syllable, the letter is not doubled. For some -s endings, doubling is optional but less common in Australian usage:

differ     differed     differing

chorused     chorusing

focus     focused/focussed     focusing/focussing

Changing verbs and nouns ending in -y or -ie

For verbs and nouns ending in -y, change the y to i before endings starting with e:

bury     buried

berry     berries

For verbs ending in -ie, drop the e and change the i to y:

die     dying

lie     lying

stymie     stymying

tie     tying

but

dye     dyeing [colouring, to be distinct from dying (ending life)]