Here are some rules that I follow to get my chains to 40:
Do not enter anything directly vertical/horizontal to your current position
Do not enter a patch that is shaking directly next to another patch
Enter the same type of patch every time
Edge patches ARE safe. I cannot stress this enough, this is why it's possible to chain in smaller areas
Enter the same type of patch every time. I reccommend always choosing the violently shaking grass as opposed to the others since it's easier to distinguish
Do not enter any patches that are only a step or two away
If multiple patches fit the rest of your chaining criteria, reset to avoid breaking. Better safe than sorry.
I'm pretty sure that covers everything important. A lot has changed but a lot has remained the same. I'm finding it easier and easier to chain using the radar as I get more practice with it. Good luck!