And in regards to your question, start low, work your way up.
I'd start with:
TPA Stawberry: 4%
FW Kiwi: 3%
TPA Vanilla Swirl: 2%
You will probably need to bump some or all of the flavours up a percentage or two (I wouldn't suggest going more than 3% higher with either though), but this should be a good starting point. Take it slow, and have a browse around here and wider interwebs to see how other people have used these flavours, what they've used them with and what others have said about them.
Enjoy!