One of the biggest things you can do is reach out to people currently outside of your school district who are familiar with the activity. There are plenty of universities in the Dallas area (which I believe is close to your school district) who participate in competitive policy (cross-x) debate. Many high schools utilize those college debaters as coaches for their teams. UT Dallas and UNT are the two that come to mind immediately.
Next, if you have a functioning team, it helps to organize the parents and have them motivated/willing to help. Your school can save a ton of money on transportation if you have a parent group that is willing to carpool your students to and from tournament. This money can be used to attend more tournaments/pay for more coaches.
One of the best ways to help your students become better debaters is to encourage them to attend camp in the summer. There are a couple camps I would recommend in Texas - the UT National Institute in Forensics and the Mean Green Workshops hosted by UNT. There are a lot of great out of state camps as well, but if your students are just starting out those two are good places to begin. I really cannot stress the importance of camp enough. It is critical for your debaters to attend camp in the summer if they want to be successful.
The National Debate Coaches Association has a ton of resources free for you to use. The Open Evidence Project hosts all of the files produced at some of the biggest summer camps free for you to download. It can be found here: http://openevidence.debatecoaches.org/bin/view/Main/
They also provide a lot of curriculum resources which you can find here: http://www.debatecoaches.org/resources/curriculum-resources/
Next, if resources are available, try to get your kids attending tournaments sponsored by the Texas Forensic Association (http://txfa.weebly.com/). Some of the conventions employed by debaters at these tournaments (faster rate of speaking, etc) can be scary to new debaters, but they will get used to it with time. Once they're more experienced, they may want to start competing on what is known as the "national circuit." These tournaments aren't usually sponsored by a specific organization, but allow students to earn "bids" to the Tournament of Champions, which is generally regarded as the most competitive tournament of the year. The reason you should try to attend these tournaments is that they are generally more competitive at higher levels and also more closely resemble the type of debate seen in college, which means your kids have much higher chances of being able to continue on to debate successfully in college if they wish to do so. Additionally, some of the conventions seen in these tournaments (open cross-examination, argument disclosure, etc) allow for better argumentation to happen.
If you haven't already, have your school become a member of the National Forensic League (http://nationalforensicleague.org/). This will allow you to join an NFL district, compete in their district tournament, and have a chance at sending some of your kids to nationals.
ENCOURAGE YOUR KIDS TO DEBATE PAPERLESSLY. Although this requires a higher upfront cost with the purchase of laptops, it saves a ton of money over time since you won't have to constantly be purchasing paper, highlighters, toner, and checking evidence tubs at airlines (if you end up travelling nationally). You can find plenty of resources to help you/them learn paperless debate at http://paperlessdebate.com/
If you don't know already, to sign up for tournaments you should be using Joy of Tournaments (http://www.joyoftournaments.com/). You create an account, tournaments are listed and sorted by state, and there are instructions for registering for each tournament.
Hope this helps!