If you've been investing for a while, you probably have learned to avoid key mistakes, such as making frequent trades based on short-term price fluctuations.

But even if you invest wisely and are able to retire comfortably, you could still make some errors in your estate planning - and these miscues could prove costly and painful to your family.

How can you avoid making the wrong moves with your estate plans? Here are a few tips:

*Communicate with your family. To reduce the possibility of hurt feelings and damaged relationships within your family after you're gone, make sure that everyone knows what they can expect from the disposition of your estate plan. Tell your children how much money they can expect - and when. (If you decide to establish a trust, you can arrange for money to be disbursed over various periods of time, or when your children reach a given age.) Are you going to leave a considerable amount of your assets to charities? Let your family know.

*Update your beneficiaries. Many of your financial assets - including your IRA, 401(k), annuities, life insurance contracts and some government bonds - allow you to designate a beneficiary. It's important to name both a primary beneficiary and a contingent beneficiary (an individual or trust who will receive the assets if the primary beneficiary dies before you).

Beneficiary designations supersede whatever instructions may be in your will, so it's essential that you update your beneficiary designations whenever your family situation changes. It's not uncommon for assets to go to the "wrong beneficiaries" (e.g., spouses from earlier marriages) or to bypass children born after the initial beneficiary designation was made.

*Maintain adequate liquidity. It's not always easy to know the amount of "cash" (liquid investments) you should keep in your investment portfolio. But as you prepare your estate plans, keep in mind that it's usually a good idea to have at least enough cash available to help your family pay for any final expenses.

*Choose the right executor. When you choose an executor for your estate, you'll want someone who has the time to devote to the sometimes long and protracted estate administration process. You also want to make sure that your executor will be fair, knowledgeable and free of conflicts of interest.

*Keep good records. Your executor and your family will need to know where your assets are located - your bank accounts, insurance policies, investments, retirement plans, etc. By maintaining an orderly record system throughout your life, you can make it much easier on everyone when it's time for your estate to be settled.

*Get professional help. You may require a variety of legal documents and arrangements - a will, various trusts, powers of attorney, health care directive, etc. - to complete your estate plans. Consequently, you will need to work with a competent legal professional, along with your financial and tax advisors. The right estate-planning team can help you avoid many of the mistakes that disrupt people's estate plans.

Here's one final suggestion: Don't wait too long to start your estate plans. They can take some time to develop, so the sooner you get them in the books, the better.