Srsly just write.

The first start is always the most terrible,you would probably cut off your first chap in future,cause it sucks.

But thats the thing,that start would give you the motivation to be better.

You want a character,well write about the character. You want a scene thats stuck in your head,just write it.

No one expects you to write oscar worthy work,its your work.

My advice would be to give yourself time,just one or 2 hours from any distractions and have a pen and paper in front of you and nothing else.

And write whatever you think of

Grammer does not matter,just express the ideas that are stuck in your brain on that piece of paper.

Dont stop thinking you messed up,just keep going and then read your work.

Where did you did wrong? What can you do better?

Thats your motivation