First of all you must have in your own mind a clear picture of, yes, what they look like, but also what type of person they are. Then you can begin to infuse their speech to reflect that.

Let's look at four types of chracter: people who are either forceful, timid, warm-hearted or critical

To convey these personalities you might use dialogue such as the following:

'Now look here, it's obvious the what we have to do in this situation is rope off the area where the dog show will be. It won't cost that much to find stakes and ropes, and we can't risk small children getting bitten by dogs. I'm sorry but it's got to be done.'

Here's someone who is not used to being countermanded. They know what they want and are determined to get it. They tend to use long, forceful sentences that defy interruption and are aimed at both parrying objection and demanding action.

'These tea cakes, well, I did try to get them right but, oh dear, I'm afraid they just didn't, you know, really come up to scratch. I dread to think what Jane will say...'

Can you imagine this dear old thing ever saying boo to a goose? She's too worried about what people think of her and too self effacing and lacking in confidence to stand up for herself. She speaks hesitantly and her sentences are broken up so that her uncertainty and timidity are revealed.

'Nonsense, Elsie, they look absolutely scrumptious to me. People love your tea cakes, you know they do. Come on, tell you what, I'll help you get them in the tin and we'll take them along to the fete together shall we?. Then we'll go and have a nice cup of tea.'

Here is a warm, generous, motherly person who is helpful and kind. She loves taking people in hand and warmly encouraging them along. Her speech is soothing and reassuring. Even the 'Nonsense, Elsie' has the positive intention of making Elsie reconsider her opinion of her cakes and of herself.

'There just aren't enough tables out. And what if it rains? These marquees should have been much bigger. I told the chairman this would happen but, of course, he wouldn't listen to me.'

This person has difficulty finding anything good to say about anything and has probably become somewhat bitter because making friends is not easy when you are so critical. They talk in short curt sentences which are couched in such a way as to rebuff disagreement or comment.

I have given just four types of personality here, but there are many more for you to experiment with. Practice writing dialogue to emphasise your own characters personality traits. You will find they will be much more enjoyable for your readers to listen to.