How to play Scrabble? Best to play against one person. I did and hated any game where it came via several people because it makes a nonsense of strategies. I used to learn a lot of two and some three letter words, though the online version is different in what is allowed and not. It is always easier to get a 7 letter word out early, so make it difficult quickly. Close down loose words by putting other words all over them - don't go out if you don't have to, and don't let the other player get to the high powered squares. Try and use higher score letters to the maximum power, and that means running both directions, and better still on a high powered square. Towards the end, reverse the tightness and, with some guessing of the other's tiles, try and make a way to get rid of final letters. It can, at times, decide who wins.
I used to play my mother, and she played to put out words, whereas I played to put out letters on positions. Words were just a filter. I didn't always win. Dominic above plays like I do, so I reckon keep playing and he'll win about half the games. In the end, the letters make a lot of difference, and if both play to exploit the board then they will make all the difference.