How often have you agreed to take on a new client or project after being asked "Do you offer this service?" when you really don't.
Your gut reminds you that 1) you don't have the qualifications or skills to handle this project, 2) you hate to do the task(s) involved or 3) you are not equipped to complete the project efficiently.
I'll admit that I've done it more than once, and have regretted it every time.
Some of the rationale that comes into play could be:

• If I say no, they'll think I can't do anything and never call me again.
  
• I could really use the money.
  
• I really want this client for my portfolio.
  
• I've always wanted to learn this skill.
  What a perfect opportunity.
  (I'll quote a lower fee, of course).
  

Most new entrepreneurs, especially those who haven't taken the time to properly define their target client or clearly define their services, feel that they have to be all things to all people.
If you are one of those people, reflect on this question: Do I really want EVERYONE to be my customer? If you are honest with yourself, you'll admit that there are people with certain personalities, ethics or work habits that clash with yours, and for no amount of money would you work with or for them.
Here are some things that you can try to make your life easier:

• Take a piece of paper and split it in 2: On one side list all the services/tasks/abilities/experiences you love to do and are really good at-Highlight a few items that you'd like to carve out as your specialty.
  On the second half of your sheet, list the services/tasks you can't do, don't want to do, and HATE to do.
  Keep this list handy; it will change, as you get more clients and more experience.
  
• Take the items on your "Things I love to do and am really good at" side of your paper and list them on your website, letting potential clients know what services you offer (listed) and which ones you don't (not listed).
  
• Quote a higher than usual fee and estimate more time than you think it'll take to complete the project.
  That way, if they decide to hire you, the higher fee will make it worth your while for doing a less-than-desired project (or make it more bearable to work with someone with a more difficult/demanding personality) and you will have bought yourself some time with your time projection.
  
• Joint venture with a few non-competing service providers so you can say you and your "partners" or "colleagues" offer such-and-such a service.
  Then outsource the project, or parts of it, to your joint partners.
  
• This is my personal favorite: If you are approached by a potential client who has a project that really doesn't get you excited, tell them that at this time, your practice is too full to take on any other projects, but you'd be glad to put them on your waiting list.
  If the project is urgent or they refuse your offer, ask if they'd like you to refer them to someone else.
  At least they'll remember you as a busy, successful, professional, resourceful and helpful entrepreneur.
  

Remember, if your gut just tells you to run away from a project, learn to react to that instinct (professionally, of course).
It will rarely disappoint you.
Besides, there's nothing wrong with saying "No, I'm not interested in that type of project.
" An intelligent and insightful colleague, Nicole Allio, once told me "No is a complete sentence.
" How true.