At an advanced level, the objective is to solve the first layer Cross in eight moves or fewer.

1) Plan the Cross.

Prior to beginning the solve, allocate time to plan out the Cross. During speedcubing competitions, there's 15-second of inspection time, often utilized for devising the Cross strategy, and sometimes more!

2) Cross on Bottom

For advanced solving, construct the Cross on the bottom layer. This negates the necessity of rotating the cube during the solve, thus conserving precious seconds in speedsolving.

3) Insert cross pieces relative to each other.

At a beginner level, Cross pieces align with the center colors when oriented to the first layer Cross face. In advanced solving, pieces are inserted into correct slots relative to each other. For instance, if the white-green edge resides in the bottom layer in front, then the orange-green edge is positioned to its right, irrespective of the second layer center colors. Once all four first layer Cross pieces are in position, only then is the first layer rotated to align with the middle layer centers.

4) Minimise Moves

Be mindful of how moving one Cross piece affects the positioning of others, aiming to minimize unnecessary movements. Sometimes, relocating a piece can inadvertently improve the position of another Cross piece, facilitating easier insertion. However, there are instances where moving a piece may worsen the position of another, prompting consideration of the sequence in which pieces are placed. This strategic approach ensures that you don't make more turns than necessary, optimizing efficiency in solving the Cross.

Resources

CS Timer has the function to give you optimal cross solutions for each side given a specific scramble.

The image below shows a seven move white cross solution for a specific scramble.  The cross solution is performed with yellow on tope and green in front.