Show your experience honestly
Put your past experiences on the table and let the employer see exactly why you're fit for the position. Foremost that helps you is honesty. It is better to be honest about what you've been doing for the past three years with a job of commission selling. You're going to have to describe what you've been doing and highlight what the job has been and also be prepared to highlight the skills you have that are transferable to other types of jobs. Hands-on experience is a very efficient tool for salary negotiation.
Be candid about change
At the interview stage be candid talking about your desire to change career paths, making it plain that commission selling simply isn't the best path for you, but that you have skills that a prospective employer is looking for. Do not simply flash your past job titles. Demonstrate exact examples of what you've accomplished. If you've increased department sales or doubled your productivity in six months show it.
Salary offer: let employer do the talking
It is common to see salary being the basic part of most of the negotiation. It is better if the employer makes the first offer. In the long run it pays to talk about the actual salary after you've secured the position as it is much easier to negotiate since you'll know that the company wants you on board. Then there is also an element of ease by which talks can be initiated. However keep a realistic range in mind when salary expectations are asked so that you can accomplish what you have set out for. Commission selling has not worked and you are now switching jobs anyway. Be frank about it, Let your strength be highlighted for which you're being considered.
Your position should excite you
All employers wish to see motivation as key to good productivity. Let this emotion be clearly visible in your face in order to show the employer that the only thing stopping you from taking the job is a decent compensation.