This common grouting mistake is easy to fix by turning the float diagonal to the tile joint lines. Spread the grout in a long sweep with the float moving at a 45-degree angle to the joints.

Before beginning to repair cracked tile without removing it ... but be sure to avoid the grout. The epoxy should be fully dry ...

You don't necessarily need a professional to help you install tile, but you do need to make sure your joints are the right ...