Because of the complexity of tax laws, I would even consider consulting with a tax proffessional who deals with tax laws.  While this might seem to be an unnecessary expense, it will guarentee against you making any mistakes in this area when tax time comes around, and as I am sure you know, IRS related penalties can be severe.   Either way, being that your daughter is 24 years old, it really is a good idea for her to get a job, so she can at least have some money, as well as file her own tax statements.

As far as i am aware of,  your daughter has to be unmarried and below 21 years of age to be eligible. BTW, what type of visa do you hold....

You can find the information you need on the IRS web site at http://www.irs.gov/pub/irs-pdf/p970.pdf. Your daughter may be too old to qualify for you to claim education credit for her. To claim her as your dependent, and therefore claim the education credit, she must be a full time student under age 24. See http://www.irs.gov/publications/p501/ar02.html#en_US_publink1000220708, 'Your child was under age 19 (or under age 24 if a full-time student). (A child born on January 1, 1991, is considered to be age 19 at the end of 2009; you cannot make the election for this child unless the child was a full-time student. Similarly, a child born on January 1, 1986, is considered to be age 24 at the end of 2009; you cannot make the election for this child.)' Your daughter may want to obtain a summer job or a part-time job so she has some income. That way, she can file her own tax return in the future and claim the education credit.