Here is where I would start. Mark you calendar for the beginning of May. You may or may not get a notice of value, it depends on if certain critieria are met. Your value increasing is one of those. Once you have determined what your 2017 market value for all the properties you own are, try and schedule an appt with an appropriate appraiser. The main types are: residential, land, commercial, and business personal property. The first thing I would do is ask for an appraisal card for all your properties and next make sure you have all applicable exemptions. Then ask the appraiser to translate the shorthand on the card to words both of y'all can understand. Every CAD is different in their terminology, trust me I know. I just took a new job at another district and I have to relearn their new system. Once you have an understanding for what buildings you are being valued on, make sure they are physically there. Nobody is perfect and lot lines arnt painted on the ground. There should be some line items regarding deprecation. Physical depreciation is the main one with functional being above and beyond the physical condition (cracked slab, leaks in roof, etc) get a feel for what the numeric value means as far as the loss in value. Now is where things get fun. Your value is based off of sales of similar types of property in a similar geographic region. If you really want to bore yourself to death look up USPAP standard 6. But the sales are the problem. Texas is a non-disclosure state. Unless the CAD has something special they may only get 30-40% of the sales for the county. Now that number is not a good number either because not every sale can be used. Look up arms length vs non arms length sales and the tax code definition of market value (tax code 23.01 link at bottom). So know you have a working understanding on how your value is crunched. Take your cards home and get the contact info from the applicable appraiser(s) you talked to and verify the measurements. If you feel a measurement is wrong then redraw the entire structure (hint: second story's in homes are the worst) to make sure it squares. Most if not all software rounds to the nearest foot and measurements are taken from exterior wall to exterior wall. Provided the deprecation, classification, and measurements are correct you make the determination if that value is more than the market can bear.
So then you need to file your notice of protest and have a hearing before an appraisal review board, basically you need to prove the CAD is wrong in how they determined your value. If your gripe is on taxes then you will get nowhere. One thing that helps a lot is bring lots of pictures. After your ARB meeting you can further challenge the value through binding arbitration or district court. I've sat through some goofy board hearings, the boards are typically very fickle and inconsistent. And lastly the board hearings are not the time in which the process needs to be explained. If you have questions about that, you should have addressed it before that hearing.
The real problem we have had is realtors and taxing entities. Realtors eat what they kill, it's in their best interest to list a property as high as possible to earn the highest commission. As they do and people buy at the higher value, values go up. Last year I took a survey of 110 listed properties in the county i came from. Using the updated 2016 value 9 where below our value and 5 where out of state owners(possible non market value sale) One was right at our value. The other 100 were listed above our value. Using the full array of numbers the realtors were about 22% above our value. So what that means is if the 2017 buyers don't talk down the owners by 23% value will continue to rise.
Taxing entities are the next issue. They set their rates on a value. So if you can visualize it as values increase the tax rate should decrease to generate the same tax revenue. BUT THE TAXING ENTITIES DONT LOWER THE RATE. They bring in gravy money because they aren't lowering the rates. If you need to see this mathematically I can show you.
So that's why people want to hire a tax agent. But keep in mind the tax savings in dollars vs the tax agent fees. Taxes are based on a rate. Typically around 2%. Some places are higher and some are lower. So you have to weigh what I would cost to higher a tax agent (some are flat fee, some are a percentage of saving) vs not. If the agent saves you $400 and you pay the agent $400 it's a wash. And most agents do very little to try and lower the value or maybe I just came from a pissant county and it wasn't worth their time.
So if you made it this far congratulations, you should have a very basic understanding of the appraisal process and theory. But the best thing is develop some kind of relationship with an appraiser at the CAD and get an understanding on how values are calculated.
http://www.statutes.legis.state.tx.us/Docs/TX/htm/TX.23.htm