Hi @ansariansarimubashir, welcome to the world of automation, there are a few good tips already but one thing would be to only go towards the more complexe apps like Rule Machine and Webcore until you are really confortable setting up simple automations.
I would point you at looking at basic rules, simple automation rules and visual rules builder. A combination of these 3 built-in apps will get you 95% of the way. Then when you are confortable, graduate to the more complexe rule builders like Rule Machine and other 3rd party options like webcore. They are not that hard to learn if you already have some basic logic.
Try them and adopt what you feel confortable using, there are also many 3rd party apps to do almost anything and the first one you should install is HPM (Hubitat Package Manager), it's an app that will help you find and install 3rd party apps that have signed up to be in HPM. Not all apps are in HPM and you will have to check the forums to find the ones you want just in case.
Have fun!
As for devices, another very popular device line is Zooz, they have really nice devices, great support, Hubitat supports most with built in drivers but there are also advance drivers that can be found in the forums/HPM to unlock the full potential of the devices like multi-tap, LED color control and other features.
You should also look at Sinope that make solid devices that no one else makes and very nice thermostats for all kind of heating/cooling devices ^(electric baseboard, gas, boiler, etc.) with built in drivers and custom advance drivers from the community.
BUT the most important thing, research if a device is supported before buying, this is where many get frustrated and start buying stuff and later learn they don't work with Hubitat (many WiFi devices with proprietary apps).
