• Let's go by car. It's much cheaper. (or a lot cheaper)
• 'How do you feel now?'  'Much better, thanks.'
• Don't go by train. It's a lot more expensive. (or much more expensive)
• Could you speak a bit more slowly? (or a little more slowly)
• This bag is slightly heavier than the other one.
• Her illness was far more serious than we thought at first. (or much more serious / a lot more serious)

• I've waited long enough. I'm not waiting any longer. (= not even a little longer)
• We expected their apartment to be very big, but it's no bigger than ours. or ... it isn't any bigger than ours. (= not even a little bigger)
• How do you feel now? Do you feel any better?
• This hotel is better than the other one, and it's no more expensive.

Better and better / more and more etc.

• Your English is improving. It's getting better and better.
• The city has grown fast in recent years. It's got bigger and bigger.
• As I listened to his story, I became more and more convinced that he was lying.
• These days more and more people are learning English.

The ... the ...

• 'what time shall we leave?'  'The sooner the better.' (= as soon as possible)
• A: What sort of box do you want? A big one?
  B: Yes, the bigger the better. (= as big as possible)
• When you're travelling, the less luggage you have the better.

• The warmer the weather, the better I feel. (= if the weather is warmer, I feel better)
• The sooner we leave, the earlier we will arrive.
• The younger you are, the easier it is to learn.
• The more expensive the hotel, the better the service.
• The more electricity you use, the higher your bill will be.
• The more I thought about the plan, the less I liked it.

Older and elder

• David looks older than he really is.

• My elder sister is a TV producer. (or My older sister ... )

• My sister is older than me. (not elder than me)