Proper way of using a Mixing Service I want to use a mixing service and I was wondering what is the right way of using it.

I have some funds in my wallet (associated with a Bitcoin Address).

Should I generate a new address in my bitcoin client (this address would be picked up from my keypool itself right now). And after generating the address, I provide this address as the receiving address (for withdraw) to the mixing service?

Second case. Let's say I want to purchase something online using my bitcoins, like dedicated hosting service or something similar. The merchant wants me to send them the Bitcoins to their bitcoin address, but if I go through the mixing service for this purpose, it would take a very long time and transactions with merchants have to be completed fast.

In cases of mixing services like bitcoinfog, the minimum time interval is 6 hours after which the withdraw process starts.

So, what is the right way of using the mixing service?
Either of these solutions would work. 

If you mix it first to a previously unused address or send it directly to the merchant via the service (ignoring the issue of timeouts on a merchant terminal if they have such a feature) the effect is the same.

The only thing to make sure is any change does not go back into an address which has not been via a coin sharing service. This will cause a link-back to your previous transactions.

The easiest way to avoid this is to have two separate wallets, one which is only been mixed and one which has not.