Is it permissible for me to put myself forward to lead the prayer in a mosque where no one knows me if I believe I am the most deserving to lead, or should I wait for someone to put me forward, and would I be sinful if I did not put myself forward despite my deservingness?

It is not permissible for a visitor to lead the prayer (Imamah) in a local mosque unless he has the permission of those in charge of its affairs. As stated in the Hadith: "Whoever visits a people, let him not lead them in prayer; rather, let a man from among them lead them." The position of Imamate is a grave one, requiring order and agreement, and stepping forward without permission does not respect this position. This etiquette preserves the privacy of the mosque's congregation and prevents innovators and transgressors from exploiting the Imamate to spread their innovations. It is obligatory for whoever wishes to lead the prayer to seek permission first, and the regular Imam of the mosque has more right to lead the prayer than anyone else.