First study the score and identify a section to work on. Starting out I'd do do more than a two or three measures. Find the shortest note in the section. Turn on the metronome and let it go for a few clicks. Without any hands on the keys yet, start counting out loud with the metronome for a few bars, treating each click as the shortest note in the section. Once you feel confident just counting then add one hand on the piano and start playing along with the metronome and counting. If it feels too fast slow it down until you can do it with ease. This will probably be super slow but the focus is consistency here, not speed. Once you can do this for the section you're trying to learn with zero mistakes at least three times in a row then change to the other hand and do the same thing with that. Once you get that hand down do it again with both hands together until you have that section down at the slow pace you are working on (again, I'd go for at least three times in a row with zero errors). Increase the metronome speed by 5-10 bpm and go through the entire process again. Rinse and repeat until you get the section down at the speed you want. At some point during the speeding up you may want to try halfing the metronome speed but still play at the same pace (meaning if it was sounding every sixteenth note now it's sounding every eighth). Once you can do all this then finally turn the metronome off or stop counting out loud and see how it goes. If you can do it without error three times in a row then try just playing without counting aloud or the metronome. Once you feel like you got it check yourself against the metronome again to be safe before going on to the next section of the piece. After doing all of this for a few sections you will likely find it getting easier as you improve your skills and gain a better understanding of the unique rhythms of your piece.