Step 1a: White cross with yellow center-piece on T(OP)
Start with the yellow side on top (middle piece is yellow), and create a white cross around the yellow middle. In the cube below, the front side is green, but this is just an example. The only important side of the cube is that the yellow side is on top!
Step 1b: White cross with white center-piece on T(OP)
Now, you can turn around the four sides, so the rotation you do would be: L2, B2, R2, F2.
But before doing those 180 degree-rotations, you must make sure that the color of the other side of the white cross piece is matching the color of the side it is on. For example on the right side of the cube below, the other side of the white cross piece is orange, so the right side must be the oraqnge side (have the red center-piece in it). So you have to rotate the Up-side until the orange S-piece is on the side with the orange center-piece. Only after this is correct you can do the movement: R2.
- Fix the color of the right side (by rotating up), then: R2
- Fix the color of the back side (by rotating up), then: B2
- Fix the color of the left side (by rotating up), then: L2
- Fix the color of the front side (by rotating up), then: F2
Result of Step 1:
After that, you can turn around the cube to make the white face on TOP. The result must look like this:
- Minimal a white cross around the white center, maybe additional white corner pieces are already correct on the white side.
- On all sides, you have at least the middle two pieces (facing the white side) of the side color.