Level your sense heading.
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Once it's maxed, the compass will always be accurate. Until then, any time you're able to successfully sense your heading, your compass will work for a short time and then it'll start to go crazy again.
You can level it quickly by creating an extra hotbutton bar with a bunch of sense heading buttons. Then go into your key bindings in-game and add all your commonly-used keys (the ones bound for movement, auto-attack, etc) as bindings for those buttons. It'll warn you that the key is bound to more than one action, but that's what you want. Now whenever you hit one of those keys, you'll attempt to use sense heading (if it's not cooling down) as well as do the normal action for that key. Train a couple points to get started (those first 20 or so points take forever to get) and you'll have it maxed around level 10.