Share with them some of the techniques you have found to be

这是一个祈使句,中间嵌套一个定语从句.
其中,some of the techniques 是share的宾语,但是其后接一个定从（you have found ）,就比 with them 更长,所以就位于 with them 之后,实际应该是Share some of the techniques you have found to be useful with them .
to be useful是表达将设备分享后,能够使设备有用,但设备有用是发生在分享这个动作之后,所以用to do表将来.