Two-star Star Battle: what changes with two stars per row
In a two-star puzzle every row, column and region needs two stars instead of one. A 9x9 grid then holds 18 stars and a 10x10 grid holds 20.
The counting techniques still work, but a region can now have a star count of two, so a pair of regions inside two rows is a much tighter squeeze than the same layout in a one-star puzzle.
Two stars in the same row cannot be next to each other, so a row with a run of three open cells has only one way to place a pair. Look for runs like that first.
Work in pairs: when a region has two stars to place and only a few legal cells, the cells they could occupy together are limited by the no-touching rule, which often settles one star immediately.
More guides on the StarGrid page.