One of the first thing you are likely going to want to do is to talk to your bank about setting up a US dollar bank account. This should be free, although you may need to maintain a minimum balance to avoid fees altogether.
Having a US bank account is just plain handy to have, whether investing or not, especially if you ever require US dollars while travelling.
If you have a significant other, consider setting up a joint US dollar account. This gives you some extra flexibility, you can 'share' the minimum required balance, and the fewer accounts you have the better. That said, you do need to keep track of the portion of money that is yours as opposed to your significant other's.
Last, some brokerages that allow you to have a US dollar side to your investment portfolio require a US dollar bank account in order to fund them (usually by money transfer or money order).
Most non-registered accounts have a Canadian 'side' and an 'US' side. A lot of the time, the US side won't be activated by default. This means that if you were to sign in to your account on-line and look at your portfolio, you would probably see only the Canadian side. To get the US side activated, phone or email your brokerage and tell them what you want to do. Once the US side is activated, you can move US dollars into this account.
Unfortunately things are not as simple when it comes to registered accounts (like your RRSP, RESP or TFSA). For some reason the brokerage industry has been dragging their feet on this, although it is slowly starting to change. Questrade was the first brokerage to offer this in 2008 and others have been slow to follow.
Brokerages which currently offer a US Dollar RRSP Include:
RBC Direct Investing
US Dollar Conversion >