To be able to give correct advice, I would need to know your age and see what you know.
However, based on what you wrote, I would suggest you get the Faber books of studies. Even though you played guitar, I would recommend you start with Faber Primer. Each level(primer,1A,1B and so forth) comes with 3 books: lesson, theory, performance. There are extra books per level such as Christmas book.
Besides the above, I would also recommend the Hannon Technical book. Not only for the technical exercises, but mostly for the scales.
And finally, I would suggest to find a piano teacher to guide you.
Hope the above helps