There are a number of factors that can contribute to not having enough money when you retire, but the most serious are not starting to save early enough and funding other things before retirement.

Here are 10 mistakes many people make to shortchange their retirement:

1. Setting money aside for college ahead of retirement: Many people decide that placing money into their children's college funds is more important than placing it into their own retirement fund. This is rarely a good idea. While it is possible to get loans for college, the same can't be said about retirement. Make sure that you contribute to your retirement fund first, and then work on providing some help for your children's college education.

2. Believing it's OK to wait: The magic of compounding interest is an important factor in growing your retirement fund. Even when you save small amounts in your early work history, the returns earned on that money will build on the base and, over time, will likely help you come out much further ahead than if you wait until later in life to begin your retirement savings. You should begin contributing to your retirement fund as soon as you begin your first job out of college (if not sooner). This will make the question of whether you're contributing enough to your retirement fund a non-issue in later years.

3. Not taking advantage of 401(k) matches: If your company provides matching funds for your 401(k) contributions, then not contributing -- or undercontributing -- is the same as throwing away free money. You should be taking full advantage of these matches from Day 1. Even when money is tight in your first years in the workforce, contributing up to the amount matched by your company in your 401(k) plan should be a top priority in your budget.

4. Accumulating credit card debt: Credit card debt means that you are paying interest to the credit card companies instead of growing a retirement fund. It's one of the worst things that you can do. When you end up paying credit card debt rather than placing the same amount of money into your 401(k) or IRA, your retirement fund will look a lot less healthy in the long run.

5. Counting on an inheritance: Counting on an inheritance or some other type of cash windfall for your retirement is playing with fire. While your parents may have a good retirement fund for themselves, there are so many things that can happen to quickly drain that fund. This is especially true if they get sick and have a lot of medical bills or if they need to go into long-term care. You should always remember that their money is theirs and not yours, and they are free to spend it any way that they like. If you do receive an inheritance, it should be looked at as an added bonus. But you should not count on it for your retirement fund.

6. Buying more house than you can afford: Purchasing a bigger house than you can afford can do huge damage to your retirement fund. This is because you're placing all your money into your mortgage instead of investing a portion of it for retirement. While a house does have some tax advantages on the mortgage loan, they are not nearly as good as the tax advantages of a 401(k) plan or an IRA. It's also much more difficult to get your retirement money out of the house than from a retirement fund. While housing as an investment is something you might want to consider to create more wealth, your own house should not be viewed as a retirement investment, and you should make sure that you can pay your mortgage and contribute to your retirement fund at the same time.

7. Neglecting insurance: Insurance exists for a reason: to protect you against an unlikely but high-cost event such as a fire, an unexpected serious illness, a natural disaster or a major auto accident. People who forgo insurance in an attempt to save money run the risk of putting their entire retirement savings in jeopardy if an unfortunate event takes place in their lives. You want to make sure that you are adequately insured to prevent this from happening.

8. Failing to take advantage of IRAs: You should be taking advantage of IRAs from the day that you are able to. If you fail to do so, it can be a huge blow to your retirement savings, since there is a limited amount that can be invested each year. IRAs are set up specifically so that you can maximize the amount that you have when you retire, and if you forgo them in your early years, you will do great damage to the amount available in your retirement fund when you get older.

9. Investing too conservatively: Investing too conservatively in your retirement fund means that you will not grow it adequately to meet your needs when you retire. You need to take into account that over time, inflation will take part of the purchasing power away from your retirement fund. As you get closer to retirement, you can make your investments more conservative, but in the early years you want to make sure that you are not investing too conservatively to yield the gains you need for retirement.

10. Investing too aggressively: While you don't want to invest too conservatively, you also don't want to be investing in things that promise huge returns but are extremely risky. You should determine a set amount of money each month to put into something like a stock index fund for your retirement. If you can spare more money after you have contributed to the retirement fund, it is acceptable to invest in something a bit more risky. However, you don't want to be risking the main portion of your retirement money in risky investments that could very well leave you with no money in the end.

By keeping these retirement fund pitfalls in mind, you can help ensure that you have plenty in your retirement fund when the time comes.
Jeffrey Strain has been a freelance personal finance writer for the past 10 years helping people save money and get their finances in order. He currently owns and runs