Do you often find yourself struggling to say no in certain situations in case you offend someone or make them think badly of you? It may be a self-esteem issue or you may just be the girl who wants everyone to be happy but either way, you're running the risk of coming across as a doormat if you happily accept every request that's thrown your way. You're probably also wishing that you could put your foot down but not quite sure how to go about it without upsetting people.

"You may not want to say no to someone who asks you to do something you can’t or don't want to do, but it's crucial that you learn to do so," says Vera Peiffer, author of The Duty Trap: How to Say No When You Feel You Ought to Say Yes. "If you don't say no, you'll be constantly disgruntled and starting to dislike the other person. They, on the other hand, will not know what's wrong, and a previously good relationship can begin to deteriorate."

Learning to say no can be difficult when you've got into the habit of repeatedly saying yes but there is one helpful strategy that you can use if you're caught on the hop.

Buying time

Yeah, you heard that right. If you're not good at thinking on your feet, you probably find it hard to offer up a plausible excuse to get yourself out of the situation. To avoid having to do this at all, try buying time. Phrases like "I'm not sure whether I'll have time to do this", "I need to think about it", and "I need to check my diary" are some commonly used examples of this. "Buying time will give the other person a signal that you may not be able to fulfill their request, so they are more prepared that you may tell them that you can't or won't do it," advises Peiffer.

Buying time won't always work though, and it's good to know the strategies for standing your ground and saying no in common situations that you might find yourself.

How to say no to... a date

Most of us are flattered if we're asked on a date, but that doesn't mean that you need to accept if you've got no interest. Peiffer recommends using polite excuses as get-out clauses in this situation. For example, "I'm really flattered that you’re asking me out but I don't think that I would be right for you" is a far less bitter pill to swallow than "I don't think you would be right for me." Other possibilities include "I'm really flattered but I don't think my husband/boyfriend would be too happy about it" and "Thank you for the offer but I've just met someone and I hope that things will work out."

How to say no to... an invitation

Open-ended excuses are the name of the game here. Peiffer suggests simply saying "Thank you so much but I won't be able to make it" or "Thank you so much but I've already arranged something else for that date." There's no need to come up with elaborate reasons for why you can't go, and you might accidentally trip yourself in the future.

How to say no to... cold callers and doorstep sellers

Be firm when it comes to dealing with cold callers and people selling door-to-door. Tell them "No, thank you" in a polite but decisive manner and shut the door, Peiffer advises. We all know how persuasive these type of sellers can be if they're given half a chance so you need to cut them off before they can get into their spiel.

How to say no to... friends requesting loans

This can be at tricky situation, especially if you've lent them money before. "If someone asks you to lend them money, you may have to consider what their track record is," suggests Peiffer. Think about whether they've previously borrowed money (either from yourself or other people) and whether they paid it back. Saying something like "I'm sorry, but I'm really struggling myself" or "Sorry, but I just don't have that sort of money to lend to you," can make the refusal seem less personal. Alternatively, Peiffer suggests making it clear that it's not your "policy" to lend money, especially if the friend in question hasn't been very quick to pay back loans in the past.

How to say no to... your kids

Peiffer stresses that staying calm and being consistent are both key. "Say no and give a reason why it's not possible, then move on to another topic," she advises. "If you keep getting pestered, say no again and give the reason again." If your child repeatedly complains that you need to buy them something "because everyone else has it", it's time to test how strong their want is. Peiffer suggests asking him or her to compromise their desire for the previous item on the list ("I can't afford it if you also want an iPod") or challenging them to work for the privilege of receiving the desired item ("I can only let you have this if you do XYZ for X number of weeks.")