It’s hard enough to save and plan for retirement. So why make it even more difficult by committing costly mistakes?

Here are 5 blunders that can derail your plans to retire in comfort and peace.

1. Following the herd

Who cares if everyone on Wall St. is planning on buying Facebook shares or the “hottest” mutual fund of 2012? That doesn’t mean those investments are right for you.

Stick to an investing strategy that fits your own personal, long-term investing goals and needs – even when all your friends, family and co-workers are doing something else.

2. Being your family’s human ATM machine

Admit it: are you the person that relatives and friends always come to when they’re in a financial pinch and need to “borrow” money? If you’re everyone’s personal ATM you could be setting yourself up for long-term financial trouble.

Once established, those kind of patterns are hard to break … That’s why many retirees have jeopardized their own retirement simply because they can’t muster up the courage to say “No” to their kids … and grandkids too!

NOTE: I know this is true because I’m also money expert for AARP.

I recently did a month-long, online Debt Challenge with AARP members and I was shocked at many people said they were in debt or hadn’t saved enough for retirement due to giving/loaning money to family members.

3. Letting money be your sole focus

We all know that you’ll need a nice nest egg to retire in comfort. But the financial aspect of retirement is only one aspect of the equation.

Happy, successful retirees say they did save and engage in financial planning.

But they also did a lot of planning based on other important factors: like maintaining good health, considering their proximity to kids and grandchildren, evaluating the weather in the state in which they retired and the amount of social interaction they had with others after they stopped working.

If these areas of your life aren’t in alignment with your goals and wishes, you won’t have a satisfying retirement, no matter how much money you have in the bank. Read 5 Secrets to a Happy Retirement

4. Having a dreamer mentality

Lots of people’s ideas about planning for retirement amount to little more than crossing their fingers and wishing for the best. Instead of doing practical steps today — like contributing to their 401(k) or starting an Individual Retirement Account — they simply do nothing and say “it’ll all work out somehow.”

The truth is that those people are fooling themselves with dreams that their Golden Years will be better than the present. Unfortunately, it just doesn’t work that way.

If you’re scraping to get by now, or are living paycheck to paycheck, it’s only going to get worse in retirement.

Just ask the millions of Americans living on Social Security as their sole income source. The average Social Security check is only about $1,200 a month. So if that’s you can rely on once you stop working, it’s going to be rough for you.

5. Paying excessive or hidden fees

Whether it’s high commissions on your 401k plan or other costs that you routinely pay, recognize that fees everywhere can cost you – big time.

These costs range from bank fees on checking accounts to student loan costs to interest plus annual credit card fees, and more.

But just look at your 401(k) plan alone: high fees can eat into your investment return, costing you tens of thousands or even hundreds of thousands of dollars.

The typical fees associated with mutual funds can range from an ultra slim 0.2% to as high as 5%.

And what happens if your fund charges you, say, 1.5%? Believe it not you’ll lose about $100,000 over time, compared with a person paying 0.5% in fees, according to a GAO report.

So all other things being equal, if you have two funds that perform about the same, always go with the lower cost fund. Index mutual funds, for instance, are generally cheaper/lower cost investments than are actively managed mutual funds.

Ultimately, it’s up to you to pave the way for financial security in your Golden Years. It will help plenty if you can avoid these five costly mistakes, which can sabotage your retirement.