The 18-count Aida has smaller grids than 14-count and 16-count fabrics. The ideal number of strands is 1 or 2 depending on how dense you want your stitches to be. There is no right or wrong when it comes to the number of strands to use for your cross-stitch. This is the reason why this craft gives you more control over your project. If you want your design to have that full and 3D look, you can use more strands. The only issue that might arise from using too many strands is the look of your stitches. Since they are dense and too closed with each other, you could hardly see the “X” figure in your stitches. Some cross-stitchers still prefer to see the “X” stitches in their fabric, so they only use 1 to 2 strands of floss. Again, the choice is yours. There is no hard rule about this.