How to Prevent Crashing Mods in GTA: San Andreas

The Game likely is going to crash because of having multiple vehicle mods installed in the game which most recent vehicle mods released are using custom strings inside these files(Vehicles.IDE, Carcols.DAT, Carmods.DAT and Handling.CFG)

If you want to have vehicle mod in the game, and replaced the .DFF and .TXD files inside the GTA3.IMG, Be VERY CAREFUL when replacing strings inside one of the 4 files listed up here

Also you should use ModLoader for very easy installation(Drag and drop inside the modloader folder)

Link for ModLoader (Compatible with GTA Vice City and San Andreas) 

http://www.gtagarage.com/mods/show.php?id=25377

Actually ModLoader says that it's compatible with GTA 3 but when I installed it required Ultimate ASI Loader (Only For GTA 3) then when I want to modify Claude's .DFF file it doesn't affect it so If you want to replace any files inside GTA 3 or Vice City's GTA3.IMG or GTA3.DIR use IMGTool 2.0

Link for Ultimate ASI Loader(ONLY FOR GTA 3)

https://github.com/ThirteenAG/Ultimate-ASI-Loader/releases

Link for IMGTool 2.0 (Compatible with GTA 3, Vice City and San Andreas) https://www.thegtaplace.com/downloads/f552-img-tool-20

Also your game is likely going to crash if you have multiple CLEO scripts installed because of incompatibility or conflicting with other scripts installed

Link for Latest version of CLEO library (Compatible with GTA 3,Vice City and San Andreas) http://cleo.li/

I hope this post helped you and don't forget to always make backups before you modify your game, because It might get corrupted and likely you're going to reinstall the game again

EDIT 4/8/2018: When installing all types of mods, Drag and drop inside a folder inside the ModLoader's folder to ensure compatibility and the lesser percentage of crashing.
Example: GTA SA/modloader/New CJ House <- thats where to put mods, I did an example
Now do your job.