1. Explain it simply
The pattern is A 比 B + adjective: 比 sits between the two things you compare.
Never put 很, 非常, or 太 in front of the adjective in a 比 sentence.
To add an amount, put it after the adjective: 大三岁, 贵一点儿, 冷得多.
For the opposite meaning, 'not as [adj] as', use A 没有 B + adjective.
2. Show examples
哥哥比我大三岁。
Gēge bǐ wǒ dà sān suì.
Older brother is three years older than me.
adjective + amount
西瓜比苹果便宜。
Xīguā bǐ píngguǒ piányi.
Watermelon is cheaper than apples.
no 很 before the adjective
这件衣服比那件贵一点儿。
Zhè jiàn yīfu bǐ nà jiàn guì yìdiǎnr.
This piece of clothing is a bit more expensive than that one.
一点儿 = a little more
今天没有昨天热。
Jīntiān méiyǒu zuótiān rè.
Today is not as hot as yesterday.
没有 = not as ... as
3. Share a tip
Drop 很/非常/太 entirely in a 比 sentence. 哥哥比我很高 is wrong. If you want to say 'a lot more', add 得多 after the adjective (比…高得多), not a degree word before it.