+1 to research! It took me a year before figuring out the mods and add-ons I wanted to do to my 2017 SR5. I drove the truck stock through any type of terrain and weather condition and made notes where I wanted to make improvements. For me personally I decided to go the route of an improved trail rig as my Tundra is also my daily driver. The first two upgrades I did were suspension and wheels/tires. I went with an Icon Stage 1 (front coil overs and rear shocks) then added a 1” block in the rear (this will be swapped out with a better leaf spring) and set the front coil overs to 2.5”. Wheels and tires I decided on a set of Fuel Zephyr, 33” tires Nitto Terra Graplers. Because our family, and a few friends of ours owns cabins and property, I know I wanted to add a winch but keeping in mind I’ll use it a couple times a month I picked up a Smittybilt X20 with synthetic rope. Bumper upgrades I picked up a set of DV8 Offroad bumpers from eBay for less than $1000 for the pair. Then I added a set of Smittybilt fender flares, an AllPro Offroad bed rack, Smittybilt awning and Overlander XL rooftop tent when our family goes camping. All of this stuff was all planned out, researched, and researched some more before purchasing as I was also trying to stay within a budget.
For your Tundra maybe start with a suspension upgrade and go from there