As a person that started playing HD about a year and a half ago and been using it eversince, here's some advice and things to do that helped me very much.
First of all, finding a skin that helps you with reading is really important. That means not only minimal lightning, small hit circle overlay and trasparent sliders (though I don't use any of it, cause it doesn't make me comfortable) but also a cursor you are comfortable with, since you will see it a lot.
Next important things is reading, which means seeing a note and identifying where it belongs on the playfield and timeline. That means playing different combinations of BPM and AR. I see no problem starting out with easy maps and slowly moving to harder and harder maps, as this is the safest way to become better at HD or even a better player in general.
I believe that practice makes perfect. Just play maps you already know well, no matter the difficulty, so you get a good idea of how different BPMs and ARs work and how to read them. Don't hesitate to memorise maps when you first start, as long as you still learn something out of it.
At the end it all comes to 'play more', and I mean both 'play more maps' and 'play a map more times' (remember that both are important in this game.
And a friendly advice to help your mindset: Generally HD is easy to 'play, for some people like me it's even easier than nomod, because you see very note twice, once when it appears and once when it dissappears, so it's very easy to aim each note. All you have to do is to correctly read the note (in terms of timing), which may be easier since there are less notesin the playfield.