Some have opined that students go for these services because they are lazy. This is partly true, but the biggest percentage that goes for these services are students who are trying to beat serious deadlines or have a deficit in their writing skills.
Dissertations need expert writing, and you will need thesis writing services. If they are up to that level, then you will have a better chance of finding a quality company. This will ease the pressure that comes with your dissertation especially to graduate students.
The regular chatting with a writer is very important as you are able to control the writing process in this way. Ideally, such a service should have a real-time chat for customers and writers. So, make sure of it in advance.
Time management is critical since your instructor has given you a strict deadline. The company should be in a position to deliver your order within the agreed time. You do not want a paper writing service that takes longer to deliver your job, hence causing you to submit the paper late. Agree with the writer, the amount of time needed to have the job completed.
Some of those sites employ non-native speakers and writers without university degrees and that might impact on the quality of their works. To avoid this, read as much custom reviews as possible. You can also check the requirements for applying on the service as a freelance writer.