Here a Summer beach from last year. I think a successful painting. I love the dark but saturated blue sky. That blue is so nice. A dark mid-tonish purple blue with manganese blue combination.
The kite helps to break up the otherwise 'boring big sky area'.
See the repetition of diagonals playing a major part in this composition too.
The thing with painting a lot of parasols is that you must choose your colors well.
Often it's good to consciously leave some colors out, or to know to add a certain color parasol in to create harmony in the range of colors. For this I use the abundance of what's just there, picking from it. There are paintings where I chose wrong. So it's mostly intuitively, seeing what works best in the chosen color range.
White parasols are always a good (the best) choice I think. And I love the red+white ones too most of all. Dark blue ones don't work so well. Test it out.
And a very saturated palette: