Walk in to Tim Hortons and stand in the line to the counter. If you are there during the morning or lunch time, there will likely be a line. When you get to the counter, greet the cashier.
Order your coffee in one of three sizes. Tim Hortons sells medium, large and extra-large coffee sizes. In the Unites States, these are 14, 20 and 24 oz. cups. In Canada each size of cup holds less than in the States, with 10, 14 and 20 oz. being their standard cup sizes.
Inform the cashier what you want in your coffee using the correct lingo. One sugar and one cream is called a regular. Two sugars and two creams are a double double. Three of each is a triple triple and four of each is a four by four.
Grab a napkin or ask for a double cup. Tim Hortons doesn't offer coffee cup sleeves like some of the other coffee shops you may frequent. The cashier may or may not allow you to have a second cup for insulation, depending on the management of that particular store, but you can always use napkins as insulation for your hand.