Jeez, I thought I just gave you some. Your question is pretty vague. What exactly are you expecting to hear? I would expect you access the public land via truck or boot leather and scout for antelope. Find one you like, get within your comfortable range (preferably down wind and/or with the sun behind you) and make a shot.
So you have access squared away. Do you:
1. Have a Rifle of adequate caliber (assuming rifle and not bow, you didn't specify) and the range time to be comfortable shooting rifle at a variety of distances from multiple positions?
2. Have a pair of broken in boots?
3. Plan for inclimate weather and bring a variety of clothing options
4. A plan to get the carcass back to your truck to butcher
or
5. The knowledge to break down the animal in the field?
4. A plan to keep the meat cold?
This is your brothers 3rd time right? Maybe ask him.