Decide on the size of your tote bag. Design a larger one to be used for groceries, overnight bags or for holding craft projects. Smaller ones can be designed for handbags or for toting smaller items.
Make a template (pattern) out of the size tote bag you have decided to design. Use poster board, which can be found in art stores or art/school supply departments, to make a sturdy template. This will allow you to design additional tote bags, of the same size, at another time.
Consider if your tote bag design will have outside or inside pockets. Make templates for these additions, as well. Also, pockets don't have to be just square or rectangular, although you may decide this works best for your design. Consider a heart-shaped pocket on the front of your tote bag, or more than one pocket. This is a unique aspect that will make your design original.
Use the pocket to create a personal design. By embroidering, silk screening, beading, hand painting or stenciling on the pocket, before it's attached to the tote bag, you have an opportunity to switch it out if you don't like the work or make a mistake. It's also easier t work with a small patch of fabric, as opposed to the whole tote bag.
Attach handles that are made from the same tote bag fabric or from ready-made trim. However, you can use other design ideas for the handles. Consider other sources for tote bag handles. Choose from handbag handles from a purse supply site (see resources below). This is especially nice when making a tote bag that will be used as a handbag.
Purchase ready-made, blank tote bags (see resources below). There is no rule that says you have to make your own tote bag, when designing. You could even add the additional design of your own pocket to the outside of a premade tote bag.