So, some advice is read the owners manual... several times. Make certain you are familiar with it. I know this is THE MOST BORING thing anyone could suggest but it could end up saving you thousands of dollars and even a life, so it's critical. You can download it now from Kubota.com and get the reading part out of the way before the toy even shows up!
Realize the weak points in the unit, places were nasty things can go wrong in a hurry as well as the slow, sneak up on you, kind of stuff.
Tractors are actually 3 point stance devices. Don't let those 4 wheels fool you. There is a center pivot under the front of that tractor making for only 3 points of contact to the frame. You can flip a tractor as easily as any 3 wheeler out there. This is why others have said to keep the front bucket low. Mine only goes higher than my hood if I need to load something higher than the hood or to get over something. I also raise it if I need more access to the engine but I block it in the up position. Never trust your hydraulics.
Be super careful on slopes. Anything much over 10-15° and you are in jeopardy of a roll over with the wrong action. That means keep that nice ROPS bar up and sturdy when the tractor is in operation... oh yeah, and that seat belt fastened. ROPS without belt is just as lethal as no ROPS.
These machines are not dedicated earth movers. They are multi-function machines that are masters of pulling things (thusly named tractors) and everything else they do is not their primary calling. So patience with them is required when digging or doing the myriad of other things they get called on to do. Be deliberate in action, and be safe.
Pay attention to gauges, odd smells, odd sounds, etc. Those are usually warning signs something is wrong. Stop the unit and check things out if you notice something odd. A 3 minute check out of the tractor can save your engine or other mechanics. Your tractor does talk to you, learn to speak its language.
I'm sure others will chime in with additional basic info, but I've taken up enough of your time. Have fun tractorin' and welcome to the Orange club!