One idea is to use your bank appraisal if you got a loan and had one done at the time of purchase. Normally they will at least push the value down to that appraised price.
If you are in Dallas, one thing you can do is pull real comps with pictures and if your home has flaws compared to other homes, like high traffic area, foundation issues, old windows, and the like, then perhaps you can argue the comps they have used. Also for example if you had to trash the house out after a renter was in it, or if you bought a fixer, show them those pictures. Show them the pictures of the grass 2ft high.
I would also go IN PERSON, as far as I know it is NOT available online and pull what they call the run sheet. Make sure that run sheet matches what you have. I see plenty of mistakes on them. Size, beds, baths, garage #, and everything else the put on that sheet. Having it accurate in your favor can make a difference sometimes. Someone on BP just posted their home shows 300sqft larger on the tax roll than their bank appraisal. That could be an issue at $200-$300/sqft or whatever your home prices out.
If you go in person, I often hear the board reps say they want pictures to prove why your home should be valued less. So give them what they want.
Also you should ask for an evidence package of what they want to use as comps. I often pick those apart. Sometimes they will use homes from different school districts, different neighborhoods, foreclosures, and so many other bad comps. One year when I got about a $50,000 reduction, they had used homes that were in no way similar to mine, because that's all they could find in MLS.
I've seen boards go all over the place with what comps they will allow or not allow. The law says it should be the value as of January 1st, 2023....I've seen some say no comps sold after that. I've seen some say comps no more than 3 months on either side of that date. I've seen some say no foreclosures? Last year when I was in front of one board I put them on the spot before we got started and asked what date range they would allow comps? So I was able to eliminate most of the CAD comps he was using.
Also if they don't give you their evidence, they CAD person can't use it against you. I've been lucky and unlucky this way. When I quoted and distributed the law, one board didn't like it and wanted to reschedule the hearing. Also their computer operator wanted to testify against me and explain stuff...but he wasn't sworn in, so I challenged that. One struck off some of their properties they wanted to use as evidence.
One thing I feel is they are often totally unfair, cherry picking the highest comps...I used to be fair and really try hard to use similar comps...but I'm so jaded now, I typically just pick the lowest ones and use those. I don't think they've every agreed to use the number I come up with any way, so I'm just hoping for at least some adjustment.
Not sure if your county has automated adjustment, but if they do and you don't want to spend a lot of time, you can try that. I'm guessing you have to be close, maybe 3-5% discount to get auto approval, but not sure about that. You can also go 1 on 1 with an appraiser and see if they will give you what you want. That's probably worth a shot, if you don't like it, then you can go in front the board or board reps.
Good luck.