In some ways, you will find it is hard to avoid commoditization. You might be the leader/innovator and best qualified for the work, but if you achieve any level of success, undoubtedly you’ll discover competition and sometimes backlash.
One solution may be to devise personalized service extensions designed to embed and enhance your client relationships and create a more sticky circumstance, where you can maintain contact/communication and capture the opportunities for add-ons and repeat businesses.
In the AEC business, for example, consider the build-in of an offer for a free follow-up fix-up/warranty check/inspection. In the residential and possibly small-business category, you could offer a day’s free “handyman” service — for all the little jobs that are difficult for a person without the proper tools to complete, but which one of your maintenance staff can handle with ease and virtually no cost other than the day’s labour.
You might be able to build the costs of these extra services into your bid package; this may be a situation where the modest additional fee hidden in your management/overhead component will go unnoticed directly, but will seem to be a wow factor at the client end.
Or you may discover that you can package the additional services as part of an overall client value service — the maintenance or handyman contract may (should) be free for the first year or two, but from then on, you can invoice for it, generating sustainable revenue.