Using Comparisons:
There are two ways to make a comparison in English.

1.) Use more in front of the adjective.
--It's more exciting.
2.) Add -er to end of the adjective.
--A bus is cheaper than a taxi.
To complete a comparison, use than.
--I am older than my wife.

For most one-syllable adjectives, use -er: older, wiser, etc. For most two and three-syllable adjectives, use more: more recent. For two-syllable adjectives ending in -y, use -er. Note that the y is changed to i in words such as busy (busier) and pretty (prettier).
It is sometimes hard to decide whether to use more or -er in a comparison. In fact, there are many common adjectives that use either form (such as able, angry, cruel, friendly, polite, quiet, simple, etc.). Listening and practice with speaking the language will help you more than any number of rules. Finally, note the following irregular forms:
good-->better
little-->less
bad-->worse
far-->farther
Adverbs can also be used in comparisons. More is used with adverbs that end in -ly:
slowly-->more slowly
careful-->more carefully

Use -er with one-syllable adverbs: faster, harder, sooner, closer, etc.
Note these irregular forms:
well-->better
far-->farther
badly-->worse

Using Should:
One of the meanings of the modal auxiliary should is advisability:
--You should leave right now.
--They should fill out this form. You can also express the same idea using either ought to or had better:
--You ought to leave right now.
(You had better leave....)
--They ought to fill out this form.
(They had better fill out....)
Should and ought to both mean that something is a good idea. Had better is usually stronger, implying a warning of bad consequences.
The negative of should is shouldn't. Ought to is not usually used in the negative. Often you will hear people pronounce ought to as otta.

The Past Form of Should:
To form the past of should simply add have + past participle:
--I missed my plane this morning. I should have left earlier.
--I can't find a hotel room. I should have made a reservation.
The past form of should conveys the notion of a failure or omission. Note that the customary pronunciation of should have is should've or shouda. The negative form is should not have, pronounced in colloquial English as shouldn't've or shouldn't'a.