izigame.me

Sims 3 very gud, game is no longer supported by EA (thank f*cking god) so you can download all paid content and DLCs from online sources and not have to worry they'll download a file checker or force you to use their origin launcher. It just has a base launcher that minimizes to your tray (that can be disabled if wanted)
Run the game atleast once, and let it slowly chug its way to you being able to make your first save. No matter how long it takes it atleast ensures that the bare minimum scripts have ran and will allow you to mod your game later if desired. If it runs perfectly then stop reading and enjoy the game.
If you experience crashing after running the game multiple times, please download the Mod "Sims 3 GPU Add-On Support" from Nexus Mods; as the description says "This is an easy app that adds most of the GPU after year 2013 to the list and its rules."
Follow the instructions of the mod and please read the disclaimers and adjust your games settings appropriately as to not have your game have the wrong graphics setting and accidentally damage your system; or overheat your room.
Mod says you must OWN basegame, idk how valid/true that is; i feel its the bare minimum morally if you want a better experience. (Fuck buying the Dlcs and the Sims 3 store content though, i wont judge you for not buying it and 'procuring' it from other sources.)
Next google Nraas and go to their website, the orange and white will blind you a bit but once adjusted look at the right of the page at the column of orange and yellow mods and download at minimum:
ErrorTrap = ( intended to catch and correct data corruption errors that can render a save-game unloadable)
Overwatch = (( act as a periodic clean up system for correcting errors and eliminating junk)Winton))
Saver = (prompts the user to save after a given amount of play-time. By default, the mod will wake after 30 minutes)
Place everything into your sims 3 mods folder in your documents folder (c:user/YOURNAME/Documents/Electronic Arts/The Sims 3/Mods)
If you don't have one; make a folder called Mods, and in the Mods folder create another one called "Packages"
Download a Sims 3 Resource.Cfg File and place it in the Mods folder. If you get any errors remove the old resource file and remove any extra files that may be unnecessarily populating your Mods folder.
To Install Mods download it to your computer, open/unzip the file to get the .package file (macs will need Keka for extracting i've heard), and place them in your packages folder. If its not recognized or doesn't show up at the main menu with its little pop-up that lists mods installed; then it may be better to have it inside the Mods file itself, instead of your packages file. Alternatively make a cheat savegame and cheat your way to being able to check if the mod is working.
I.E. More inventions on the inventing table at higher skill levels, so cheating to a higher skill level to see if your sim is able to even craft the custom content downloaded. (Old games have finicky solutions for problems, and it can just not list mods you have for no reason so a cheat save after every batch of new mods added can be a fun way to check if everything is working well together.)
Everything else on their website is up to you to personally choose for your game/experience (especially if you're a coomer), but the listed ones earlier massively improved my own experience and should help in you preventing any save loss or frame dips long term. Overwatch especially, since it will turn off active speakers, Tvs and other toggle-ables that might be taking up excess resources in the games system.
The game is a resource hog even now, so if you have everything ultra don't be suprised if you're suddenly looking down a barrel of a Throttling gun.
Not to shill another purchase to go with your Sims 3, but the application Borderless Gaming has massively improved my experience with having this game full screen and tabbing out without crashing the game. If it doesn't improve your experience please refund it before you reach the 2 hour mark of owning it and try the program Magpie. I haven't used it, but i have heard its the Free alternative to BG and may work better on certain systems.
Have fun and hopefully any problems experienced can be solved by getting a degree in googling. Many problems have had workarounds made, you just have to trust in the lengthy ass process they require unfortunately.