First, I would like to say that if you cannot afford a lawyer you should ask the court about appointing you a lawyer. Their assistance, expertise, comfort, and counsel are invaluable and can help advise you so that you can make the best of a bad situation. As far as keeping the case off your record, the ways to do that vary greatly, if they exist at all, depending on the facts specific to your case. Sometimes cases can be dismissed through taking classes, restitution, pre-trial diversion, lack of evidence, witness problems, legal arguments, or, if necessary, by being willing to go to trial and hold the prosecution to its burden to prove guilt beyond a reasonable doubt. This is a charge that, as you have said, has long-reaching and immediate consequences. I highly recommend you contact a lawyer so that they can advise you as to the law, investigate the facts of your case, negotiate with the prosecutor, and evaluate all possible resolutions with you so that you may determine what you would like to do in an educated and intelligent manner. Good luck and I hope this has been helpful. Here is a link to the section of the Texas Penal Code dealing with theft that may be informative:
Do NOT represent yourself. Most of the misdemeanor courts in Harris County will appoint a lawyer to represent you because you are a full time student. Be sure to bring proof of your being a student to court with you.
You are barely (by $8) over the class C mark for the level of the offense. If this is your first offense (and your guilt is a foregone conclusion), then you should absolutely apply for pre-trial diversion (if they will not give you a Class C deferred prosecution which they probably won't because of policy reasons.)
Pre-trial diversion is a contract with the State in which you agree to be in a probation type situation for a year - reporting, taking an anti-theft class, paying fees, community service, etc. When you finish the year and the program, you wait 2 years and you can apply to expunge (clear) your record. But, you will need a lawyer's help.
To that end, you will also need a copy of your high school transcript, a copy of your college transcript as well as proof of your current enrollment, letters of recommendation, proof of employment (you will need to work at least a part-time job to pay fees, etc. Prosecutors are hesitant to give someone PTD who doesn't have a job because of the fees involved that you MUST pay.) You will also have to write a letter of apology & acceptance of responsibility.
You can begin gathering these things to help your lawyer but talk with the lawyer about it first.
If you cannot get PTD, the next best thing is deferred adjudication probation. This can be sealed once it is completed if you qualify (considering your background history) but be aware that sealing the record does NOT remove it from you record and it is accessible.