The above explanations are exactly correct. To put it another way, a tax deduction is in effect a discount on expenses equal to the taxes you paid on that amount of income. The government will give you back the tax you had to pay on that money. So, if your marginal tax rate ( look up the definition of marginal tax rate vs effective tax rate and understand the difference; it's important to know this ) is 39%, deductable expenses will give you a refund of 39% of what you spent. But it's a discount on money you spent. For example, money donated to a qualified charity is tax deductable. So if you donate $1,000 to charity, the government will refund the $390 you spent on that donation, so the $1000 donation only cost you $610. But keep in mind that you are still down $610. A tax deduction never puts you ahead, it just mitigates the expense by your marginal rate.
If you are in the 15% marginal bracket, then your refund is $150, so you are out $850.
Here's another way to look at tax deductions: It's like buying something in a store, and the sign says, "Regular price $5,000, on sale for $4,000. Buy now and save $1,000!". Realize that if you buy it, you are not saving $1,000, you are spending $4,000. Otherwise, you would buy 100 of them and end up ahead by $100,000. These is obvious, of course, but many, if not most, people don't understand this. So you will hear people say that they want a big mortgage, and don't want to pay it off, because they get a big tax deduction. They are very wrong. A tax deduction on a mortgage means that the interest that they are paying will be reduced by their marginal tax rate. So, if they are in the 33% bracket, then a 6% mortgage will be effectively a 4% mortgage, but they are still out 4%. If you have a 1 million dollar mortgage, that 4% means you are getting a $20,000 tax deduction, in the form of a refund check, but what you are really doing is spending $60,000 and getting $20,000 back. You are still out $40,000 for the year. ( Yes, I realize that some people might want to keep the mortgage and invest the money they would have used to pay it off. Of course, those people are essentially using their house as a margin account to play the stock market. The wisdom of this strategy is debatable. Regardless, that's a discussion for another day.)
However, the above is still not quite accurate, because of the Alternate Minimum Tax as well as certain limits on itemized deductions ( The deductions equal to the first 7% of your income don't count ) mean that for most people, the standard deduction that everyone can get will give you the lowest tax bill, so you never get to use the deductions, as noted by
@operaman above. Also, in this case the job search isn't deductable anyway, as
@colbgw02 pointed out.