So far, the only things that I've installed are Mount Akina 2017 and Mount Panorama. I'm looking for more racetracks, but if you have any recommendations for cars, that would be appreciated. 👍
@Cote Dazur speaks the truth. Download
Content Manager ASAP. It works as a replacement launcher, but it is so much more than that. It organizes all of your content amazingly well and it automates or greatly improves common tasks within Assetto Corsa. The software is free for the Lite version, however, I really recommend you slip a donation to the author to receive your product code via email which unlocks the rest of Content Manager. The developer is an amazing guy with a passion for his project. He is constantly updating and adding new features (plus any decent suggestions users give him for features) and he does this in such a short amount of time usually. There is no minimum amount to unlock the full version. I only gave $5, but it seriously is the best $5 I've ever spent on my computer.
@WarriusZero is also right on the money with the free mod called
Good And Bad Weathers. The only way to use it, however, is with Content Manager, but you need that anyway.
The ~8 different weather settings Kunos supplies are okay, but GBW is a pretty hefty improvement over the Kunos weathers. There are a ton of different weathers to choose from. The clouds are so beautiful in GBW compared to the Kunos clouds, in my opinion.
I use
SideKick too. The default apps that come with Assetto Corsa are good. I actually like them quite a bit. Unfortunately, they do take up a fair amount of screen space. Sidekick packs so much information into a small, easy to see interface:
If you decide to try it, you'll see how you can click on various items that you see above to change what appears in that location.
Those apps are essentials, in my mind. There are probably a few others, but I can't really think of them at the moment.
@WarriusZero is correct - you will come across mods that are very poor quality, but if you stick to the mods that are available via Race Department, most of them tend to be at least decent quality all the way up to excellent quality. Other sites will offer so many more different cars & tracks, however, it is not always easy to tell which mods are completely awful and which ones are good. In most cases, if a particular mod is not available from Race Department that means that the car mod was probably made with ripped Forza models. And while I have several ripped Forza models that have a ton of work put into them and drive incredibly well and accurate to the real world car's performance, Race Department only allows scratch made mods that are uploaded by the developer. Of course, there are always exceptions to this. Also, there are times where I don't mind having a mod that doesn't drive well at all - I just have the AI drive those cars until I find a better quality mod of the same car.
I do think that it's better to drive Kunos cars because at least there is consistency in how their cars are developed in respect to each car's physics. Plus, they work hand in hand with car manufacturers very often, or at a minimum the car manufacturer will send Kunos data, telemetry from testing and stuff that most modders could never get their hands on to build their mod cars. It's probably better to get the actual data from a Porsche engineer than it is to just read some random website or magazine when trying to build a car's suspension or apply proper aerodynamics so things like downforce are realistic while on track.
There are a couple of track builders/converters that I would highly recommend. Here are links to their profile pages on Race Department. Just click the Downloads tab to see what mods they've contributed. If you're interested in a track, just click on the track name and it will bring you to that track's download page.
Lilski -
http://www.racedepartment.com/members/lilski.218202/
Tiago Lima -
http://www.racedepartment.com/members/tiago-lima.48002/
If you like driving on roads in addition to race tracks, there are a couple of mods that really stand out. My favorite road available for Assetto Corsa is Transfagarasan. It's a long, fun drive! There are two layouts, hillclimb and downhill. Next is a huge area called Lake Louise. There are many different roads to drive that are interconnected allowing you to have some unique sessions on this cold Canadian tourist area. Unfortunately, Lake Louise isn't completely free. There is a free version that provides you with 23 kilometers of roadway to drive. For a small donation (no minimum) you will receive the entire 50 kilometer version.
Transfagarasan link -
http://www.racedepartment.com/downloads/transfagarasan-dn7c-romania.12469/
Lake Louise link -
http://download.racelakelouise.com/
That should get you going for a while...
👍
EDIT: I forgot to recommend some mod cars. I'll try and think of some good ones and post those soon.
Is this mod available??
Even then it's really only one or two extra double-clicks, but it will make you scratch your head for a minute when the mod doesn't appear in game.
That setup... 
