Referrals from other departments
One way to gain recognition and trust is to gain buy-in on your services from one department and have that department act as your referral to other departments within the organization. An internal consultant can accumulate quite a portfolio of satisfied customers and proven results by taking this approach. If other departments can see the results first hand and hear positive feedback from their trusted colleagues, they are more likely to adopt the help of the internal consultant.
Internal consultants need to make the organization aware that their services are available. One practical way to do this is to write an article in the company newsletter or have an article written about your services from another department. Not everyone in the organization may be aware that the services of an internal consultant exist, and the positive impact those services can make.