Work from the outside to the inside on the perimeter to avoid large shifting of gems. This will prevent cascades, which cost time to recover from. Do not go out of your way for clock matches. Try to incorporate them into shifts that you have to do anyway to get the target pieces you need in place. Start grouping clocks in the same area and they will match on their own without you having to take extra time to align them. Always look at the next color gem to save time when scanning for its location.