You must Register to vote at least 30 days before the election. If you changed your address, changed your name you must re-registered.
Be sure you have the correct identification. Texas voter law is very specific about what documents can qualify as proper identification. For example, if your drivers license name does not match your name on the Official List of Registered Voters but is similar, the voter will be asked to sign an affidavit, complete a name change form, or show another form of ID that exactly matches the name on the Official List of Registered Voters.
Find your polling place. If you intend to vote early, find where and when those polling places are open; this link will give that information also.
Read about all the candidates and issues; consider who is paying for or backing the issue and whether they have my interests in mind. The words on the ballot often mean the opposite of what you think they mean. This web site will have Democratic candidate information and an analysis of the issues. Normally a link will be on the Home Page.