My USP is all about the client and what they want. I don't try to show how I'm different from other translators. No, I try to focus on what they need and where they want to get with their translation and how I can help them get there. I also emphasize that I'm in it for the long run and that I don't want to work FOR them but WITH them.
When working with clients being a good translator is often not enough. You have to kick ass at customer service, you have to walk that extra mile, you have to understand their needs, their market, their goals and aspirations. I try to forge partnerships instead of employee/employer type of relationship.I think that this is my USP.
I'm also trying to narrow my audience/services and focus on a specific niche (video game localization). Which gives me an opportunity to have a better focus and find the type of clients I want to work with. I also try to bring my personality into the game.
I think I'm lucky because I work mostly with the people who have the same interests as I do, who are in the same age group as I am and generally have the same easy-going kind of attitude towards work and doing business. I'm mean, isn't nice to have a client that pays your invoice on time, then sends you an email confirmation and then you can just send them a GIF with Tom Cruise high-fiving them (from Top Gun) and they'll have a good laugh and send another GIF back? :)
This gives me so much pleasure because I can just be myself when I talk to them and basically build something more of a friendship rather than a standard cold and formal business relationship. It's a very non-standard approach indeed, but it works for me and my business, and I think my clients value me as service provider because of that.
Talking about rates is not easy. Especially when you want to get a raise, that's why I like building friendships with my clients. That's why I rally enjoy doing a great job at customer service (maybe it might have something to do with the fact that I worked in customer service field when I was a student. I worked as a server at an up-scale restaurant/pub and at a front-desk in a hotel). I've learned a lot from those first 2 jobs. I learned how to listen to people, how to understand them and how to help them get what they want. I've learned how to be respectful and how to show people that you care.
I try to use this past experience in my work as a translator and as a founder/developer of The Open Mic. Customer is king after all. This helps me build a strong relationship where we trust each other and can be honest and have those tough "rate" talks.
I think the best time to bring the subject of rates up is when you helped your client in a major way. For example, you come through for them with an urgent request and this saved them a lot of headache and helped them launch their game/promotion/product on time, or if you're working with an agency client you might ask them for a feedback from their end-client. If it's good, and if it results into new projects and more work from the same end-client, then you can mention that as well. You did your best job, you helped them secure a great end client and more work, I think it's fair to ask for a raise, right? :)