Mistakes Small Companies Can Avoid When Working With Consultants

If you are considering bringing in help to work with you on your Salesforce implementation, make sure you have executive support for your project as well as a dedicated internal resource to own the project when it is complete and to nurture it along the way.  Make sure that the people (or person) responsible for upkeep and support of the completed project are involved early in the roles of tech lead and business analyst and that they approve the approach that they will ultimately have to support.  

Working with a consultant shouldn't be like
swimming with sharks

Those are the most essential requirements for a successful project, but you can avoid costly errors by considering the following suggestions as well:

1. Get a signed NDA.  Your data is valuable, your code is valuable.  You are turning complete access over to someone who should be happy to sign an NDA.
2. Understand your data before giving access to it.  You should know your data and have a written plan for maintaining data quality (such as best practice documents and descriptions of validation rules, workflow and triggers) or at least a plan for improving data quality (can you describe what you think of as duplicate data?). 
3. Start writing a specification for what the business should be able to accomplish when the consultant is finished and how users will be interacting with whatever the consultant implements.  Even if all you need is to have a few third-party apps installed, you should describe user access and data interactions you expect to see and define the business process you hope to address. 
4. Get the travel costs and incidentals spelled out, including maximums you are willing to pay.  And agree up front whether meetings need to be in person, or can they be online. 
5. Document in the contract who owns any code and what they can do with the code going forward.
6. Question their recommendations, most consultants want you to be an active partner and understand the work they are putting in for you.  Questioning offers a chance for early resolution if you can uncover a mismatch between their understanding and your reality.  At the very least, you stand to gain a better understanding of the solution they are offering.
7. Trust the consultant once you decide to hire them.  Not trusting your consultant is evident when you hold back information or limit their access to users and decision makers.
8. Make sure your company understands a project's functional specifications.  What is the minimum you expect the consultant's work to accomplish for you and how will you recognize when it is complete?  Involve end users and management both in this process and document their needs and processes in order to guide them through User Acceptance Testing.  Highlight for users the holes and pain points that are being addressed so they will understand the purpose of the project and what it looks like when complete.
9. Specify the project goals and how you will measure their success.  What is it that you hope users will accomplish and how will you measure user success.  For example, if you want users to be able to map their accounts and find nearby accounts when they are on the road, you can try to measure how often they use the feature, but you are probably more interested in whether more accounts are being visited on each trip so the latter is a better measurement of success.
10. Ask your consultant which vendors may be paying your consultant to sell their product into your org.  Ask them to disclose any commission they would be eligible for at the time they recommend those vendors.  There is nothing wrong with commissions, but you may want to independently look into some competitive products for your own understanding of the value of the suggestions your consultant offers.