The way I understand TFSA is that you get no tax benefit putting money in or taking it out. There are no liabilities tax wise either. The only benefit is that income earned within the account is earned tax free. You have a limited amount each year you can put in the account so I would recommend maxing it out every year. Because there is no tax implications for a withdrawl only a reduction in the total value of the account, I would think one might want to put some higher yield income earning investments in it. I am not a tax advisor so please do not take this as gospel and ask someone that knows for sure.
Rookie
PS
Once the account is opened you can carry forward any unused contribution. There is no benefit to carry it forward, so if you have any long term investments that are taxed as income the sooner you get them in the better.