Are there other ways for a model to get started besides attending a convention?

Yes. A model can travel to major markets and go to "open calls" which are small blocks of time agencies set aside each month where new models can be seen briefly by an agency representative. Although this works for some aspiring models and talent with the right look in right place at the right time...this is only one market / city. There are many markets but unfortunately the costs of travelling to all these markets can be considerable. Different agencies want different looks so even if you could travel to several major markets / cities you may never find the right agent for your look and will spend thousands on travelling expenses alone.

A model can also send snapshots to a modelling agency. Countless prospective models do this and a few get discovered this way but most are overlooked. This method is certainly the easiest and least expensive. Using this method you need to make sure that you are sending your snapshots to the most reputable agencies. If you are what that agency is looking for the next step will be to travel to that agencies market / city so they can meet you in person. Agencies do not sign models on snapshot submissions only, they need to meet with you in person and interview you first to ensure that you do have the potential, personality and availability to be successful in the industry.