1st gear shaking and very stiff clutch

[Olea]

Hi,
I've a 2008 Yaris 1.3 VVTI (Made in France), 120000km, with the problem of shaking (judders) in first gear and a very stiff clutch.
I've read many things about this problem but I still wonder what to do...
- Replace Clutch ? Which one to choose?
- Replace concentric slave cylinder ?
- Replace flywheel ? Or only pressure plate ?
- Add modified gear selector parts ?
- Replace hydraulic clutch fluid and bleed master cylinder and slave cylinder ?
- Replace gear box oil with Synthetic GL4 75w ?

Did anyone already get rid off this problem ? And what can I do to resolve it ?

Greetings from France.