Good luck with the Primals, CT, and Coil groups. As is usual in most MMOs, the biggest hurdles for tanks is gear. Consider reading
this guide on how and where to gear up. It is a little outdated, but the general gist is to supplement the Wanderer Palace and Ampador Keep runs with additional mythology and philosophy runs (story quest dungeon, low-level dungeon, and high-level dungeon roulettes, and maybe CT if you are feeling bold).
Prioritize armor pieces first (especially body and leg, other pieces of gloves, helm, belt, and boot at your own discretion). Higher level weapons will help a lot if you are having trouble keeping enmity on targets. And lastly, when gearing up, keep an eye on bringing your ACC stat to 444 (you might want to check with a devoted tank for optimal number, but I think its 444 or higher) for Coil.
If you have the time or the willpower, try to level MRD to 8 for bloodbath. It pairs wonderfully with your fight-or-flight buff and savage blade combos for some extra durability/enmity in tough fights. Foresight has some uses, but there are better skills to put in your cross-class slots (experiment to see what suits you). Stoneskin is also good on a tank, so it is good that you have it. If you are thinking of healing, you will want THM at 26 for Swiftcast. Nothing beats back an emergency like a benediction+swiftcast+medica2/cure2, swiftcast+stoneskin, or swiftcast+raise.