My initial thoughts are this can only be a success if Welsh is viewed as the primary language. Here in north wales as you drive west for example welsh is first on the road signs. It should in my opinion be a legal obligation to make welsh the priority in things like station announcements. If you think about it no welsh speaker these days will bother to wait for the welsh announcement. They have just heard it perfectly well in English.
Then there is education. This is more tricky in that the number of teachers capable of teaching welsh may be too few but if in early years welsh was pushed more then the current situation at GCSE might become better with more students getting better qualifications. However, education itself needs i think to move away from the current form of learning Welsh and move to a more conversational form.
Public bodies should do more things with the welsh language. Ireland for example has the garda. Why not have heddlu on all police cars etc?
S4C and radio cymru also need to be protected and investments made to ensure a quality provision of welsh language entertainment.
I could go on. But for me the underlying principle has to be that the language has to have priority over English. If its seen as second best many people will say why bother. So Welsh First. Or should that be Cymraeg yn Gyntaf!