Practise every day for at least 30 minutes.
Get your siting position right and make sure you are sitting upright but relaxed with a slight fall of the forearm to the keys. Don't drop the wrist.
Spend time learning the names of the notes - initially in the RH treble clef and as soon as you are confident enough learn the LH bass notes too. Write down, name and play the notes.
Be meticulous about fingering and don't move the hands around once you have found the starting notes of the first easy pieces. This will develop your muscular memory and assist progress greatly.
Try and look at your hands as little as possible and rather concentrate on following every note of music going up and down. Follow the line of the music. Is it going to the next note or is it missing out a note?
Above all, proactise very SLOWLY and hands SEPARATELY as well as hands together, because the brain needs to take in a lot of information. If that is done carefully, the speed comes to you eventually. To play fast you have tp practise SLOWLY.
Whilst practising slowly it is hard and often impossible to hear the tune. Try not to get frustrated by this: it is a normal stage to get through. As you gradually achieve more speed, the tune becomes recognisable and that's your reward for practising slowly.