E.E. 'Doc' Smith had the perfect Answer.
We cannot travel Faster than Light - bacause Mass increases the Faster we Travel.
AT the Speed of Light - Mass is Infinite ( effectively ).
This is because the INERTIA ( and Gravity ) Effect of Mass is increased, the faster we travel.
However - IF we could CANCEL the Effects of Inertia of the Mass ( this would also cancel the effects of Gravity of the Mass ) - then Einstein's Laws would not be broken if the Object ( effectively Zero Mass ) accelerates up to the Speed of Light , or even many times the Speed of Light.
The limiting factor on Speed then become literally the Friction of he "medium" of space - Gases, Dust, Dark Matter, etc.
However - the Object inside a Inetria Cancelling Field is effectively outside of "real space". To any Travellers inside the FTL Ship - it all seems normal, except that you CANNOT see where you are going.
For them, there IS Inertia and Mass Attraction ( Gravity ) inside the Field - but the "space ship" is outside of "normal space" so it will not be affected by Gravity or Masses outside.
Navigation - well, you simply point the Ship in the direction you want to go, towards a Large Mass like a Star - and switch on the Inertialess Field, and then your Frive System.
Any small Masses along your route will generally be deflected by the Inertialess Field, or disntegraed if they are very small - but this cannot work on a Large Mass like a Star or a Gas Giant.
When approaching the Star or Gas Giant - your FTL Drive will effectively "drop out", bringing the Space Ship back to "Normal Space".
This is a Gross Simplification - of a Technology which I have looked into at some depth.
However - do not ask me HOW it Works - I do not know.
For the purposes of my Stories and my Game - I can work within the Advantages and Disadvantages, the Limitations, of such an Inertialess System, and a Very Fast FTL Drive.
I do not need to Explain how it will work - but some time in the Future, I KNOW it will be able to work.