It's hard enough to devise a spending plan -- but what if, after all that effort, something's still not right? Here's how to make it all add up.

Like many people who have struggled to create, never mind stick to, a budget, McNaughton blames herself.

But as a hardworking single mom with a master's degree under her belt -- and a career that involves complex statistical analyses of medical and dental data -- McNaughton is no slouch when it comes to handling numbers.

The problem is that she's making a few basic miscalculations that repeatedly throw her budget off track. Here's how to get back on the road to financial progress:

5 steps to fix your budget

Understand your motivation. Budgets often fail because they lack a sense of purpose, says Tricia, a founding member of the Women in Red and our resident budget czar. "You have to define the reason why you're doing it. Saying 'I'm budgeting because someone told me to' won't work."

McNaughton's budget has a purpose: She wants to enjoy a better, happier way of life in retirement. "Every dollar I save is like investing in my freedom."

But she readily admits that when life happens, "I tend to drift."

The trick, says Amanda Bellamy, a Woman in Red who works for the city of Mission Viejo, Calif., is to rely on that goal as an anchor for all your spending decisions, day in and day out.

"It keeps you going in those weak moments when you don't want to limit yourself. 'But I want to see this movie or go have dinner with my friends.'"

Know your numbers. The biggest budget buster for most people comes long before they overspend, says Tricia: "You have to track all your expenses, and that's where most people drop off."

A couple of years ago, McNaughton spent six months tracking her spending -- religiously using software. So why didn't it take?

Thanks to a series of overwhelming life changes -- a major illness, a new home, a new job -- she quit monitoring her cash flow.

What McNaughton needs now is a method -- paper, digital, abacus -- that will keep her expenses front and center, says Tricia. "Record keeping is really important, especially in the beginning, when there's a tendency to say, 'Oh, spending $5 here or there doesn't matter.'"

Get real. Your budget is more likely to implode if you tighten your belt too quickly. "If you want to save $200 a month, see if you can save $50 in a week first," Tricia recommends. "Baby steps are best."

That's what my husband and I discovered when we began the Grocery Challenge with a daredevil vow to cut our $400 monthly grocery bill in half.

Ha!

After a month of missteps, we did manage to cut it by 25%. Lesson learned.

Bellamy recommends revamping your spending a couple of categories at a time. Track your groceries and utilities for a month, analyze those expenses, then move on to your personal care and entertainment spending, and so forth.

Decide on a target amount to maintain or to trim in each category, depending upon your goals.

Without regular expense tracking in Step 2, of course, you'll quickly lose control of your spending in all categories, which is what McNaughton has found. "Because I don't have a good idea of what I'm spending each month, I want to cut it down, but I don't know what I'm cutting."

Find a system that works for you. Successful budgeters agree: A workable budget is one that fits not only your money but your lifestyle and personality.

As I see it, there are two main methods: macro and micro.

Some people swear by macro methods that are based on covering the big chunks -- living expenses, savings, retirement -- and leaving the remaining cash to your own discretion. The 60% Solution is such a plan.

A micro method is based on more detailed control and adjustment of individual budget categories, transferring cash between categories as needed. The envelope system -- where you spend only the cash available in each envelope -- is a micro plan.

Bellamy adds another layer to her micro budget by timing her expenses to each of her 26 yearly paychecks. She pays one set of bills and sets aside savings with the first paycheck of the month, and then pays rent and smaller bills with the second. Her two "extra" paychecks go straight to her Roth individual retirement account.

Patrice Bishop, a faithful Women in Red reader, says she experimented with many different methods. "Long story short, none of them worked out and some even led to bounced checks," she wrote in an e-mail. "I think they failed because I was basically copying other people's ideas without taking into consideration my own personality."

Bishop ended up creating what she calls "the living budget," where she puts her savings aside first -- and then lives on the remaining $1,680 per month. Each paycheck covers her expenses because "I act as if that amount is all the money I have in the world."

Stay flexible. Life happens, and a good budget can adjust to your changing needs.

A macro method like the 60% Solution does this by having you allocate 10% of your gross income for short-term savings and 10% for long-term -- so most of life's little (and big) surprises are covered.

A micro method can be flexible because you can adjust one category to provide cash for another.

"I sometimes get in a spendy mood," Bellamy admits. She goes shopping but is careful to pluck bits of cash from other categories -- and not splurge mindlessly. "I'm careful to make sure I have the money somewhere before I spend it."

Above all, a good spending plan is and will always be a work in progress.

McNaughton says that although she has stumbled many times -- and dropped the budget ball many others -- she's ready to try again.

She is using a system she has dubbed the "on the go" method, using a paper calendar where she tracks not only the bills that are due on certain dates but the amounts she spends each day.

"I really wish I could have a fresh start," she says wistfully.

I think she's well on her way.

BY MP Dunleavey