Hi!!
Don´t worry too much about safety, the Camino is really a VERY safe place!!! For sure you have to take the basic precautions .... don´t leave your luggage unattended in the bus station (which I think are the most dangerous places), etc.
If you plan to start your camino somewhere between May and September I would start as early on May as possible (in order to avoid the pick season) . Probably I would start in SJPdP or in Roncesvalles, going up to Leon following the
Camino Frances. Once in Leon (I assume we are speaking about the end of May or the beginning of June, which means that you are already entering in the pick season) I would go to Oviedo through the Camino del Salvador and from Oviedo to Santiago following the Camino Primitivo or the Camino del Norte (which will be a lot less crowded than the
Camino Frances). Probably this combination will allow you to take the very best of every camino and you will always find an acceptable number of pilgrims from different countries.
I know it might sounds very complicated, but believe me .... it is not. Every thing is very well marked, most pilgrims and all the hospitaleros in Leon and in Oviedo can show you how to proceed. BTW, if you decide to follow this camino, take the albergue of the CARBAJALAS in Leon. They will issue the credential for the Camino del Salvador (even if you don´t need this second credential, probably you will like to keep it).
Ultreia & Buen Camino!!!