Step one of the TOC process of improvement is to identify the constraint.

 
There are a number of ways to make this step easier. Firstly, establish if you have an internal or external constraint. (It is nearly always preferable to have an internal one as you are in control of it). Ask someone senior in the organisation is it easier to generate more sales or to increase production/services?

If it is easier to get more sales than to produce more then the constraint is probably internal. Now try to find out which area of the business has the constraint in it. If you business needs to engineer each new sale – check if engineering is the constraint. If not is the problem in supply or in production itself.

If the constraint is external try to identify by talking to marketing and sales the cause of this constraint.