Uniforms and shoes are not considered employment expenses that you can write off. Everyone needs to be properly clothed for the work they do.
You can only write off employment expenses if your employer requires you to spend your own money in the course of the work. ie A builder has a young lad working for him who transports goods and materials to the job site with his own personal vehicle. The employer would give the employee a T2200 Conditions of employment to go with the tax return. The employee would then calculate his mileage traveled for work versus for personal and keep ALL fuel receipts etc for the vehicle.
There are a few expenses that would not require the T2200 such as police checks or First aid training.