Alright so be forewarned I'm really new to making content for GTA. I was familiar with importing and adding textures in GTAIV a while ago, but now I want to get into creating my own texture designs for police models. The problem is I have no idea where to start. Where do I get the basic files to design over? Should I use Photoshop for making the designs? And then do I use Zmodeler to preview the outcome of the design before putting it in game? 

Alright so be forewarned I'm really new to making content for GTA. I was familiar with importing and adding textures in GTAIV a while ago, but now I want to get into creating my own texture designs for police models. The problem is I have no idea where to start. Where do I get the basic files to design over? Should I use Photoshop for making the designs? And then do I use Zmodeler to preview the outcome of the design before putting it in game? 

If you are going to texture for GTA V then you can either download a model that has been released such as centuries's buffalo, which comes with a template that you can use to make a skin. If you want to do any of the original vehicles in game it is a bigger process because you have to use a few programs to extract the texture out of openiv and convert it to a png to be able to edit(if you want to know then I can pm you the things you will need.)-this will become obsolete after enough models are released anyway.

It will be easier though to use models that will start coming out because they will have templates you can easily use like I mentioned above. I use Photoshop to make my liveries but you can use another program like GIMP I have seen some people use. No you do not need Zmodeler to view the outcome you will use OpenIV. Say you complete your skin for Centuries's Buffalo you will open up OpenIV and navigate to the buffalo's files then from there you open up each .ytd file and replace the police sign 1 with your completed texture and then you can preview it in the .ytf file to see that it is changed, for example a livery I made for the stainer a while ago: https://gyazo.com/13cb2f8ee02db0d28e7659caef4bb3b2

 

Thanks for the guidance, for example I wanted to extract the Police Interceptor and get rid of the ugly "POLICE" on the side and replace it with the LSPD logo like the Police Cruiser (Stanier). So I extract the texture via OpenIV, make it a PNG, edit in Photoshop, return to original format and preview via OpenIV?