I would use the same type of thread (just an example only brand i can think of) like cloaks and clark you can use different thread but found that if you mix brands you can have issues with breakage and nest. I have not used clear thread heard it is hard to work with. For SID it is always best to start in the middle of your quilt this will help prevent puckers. Pin really well and you should have no problems.
(all this is info I received from the group from time to time I feel like an expert now!!) Remeber we are here for you if you get stuck take pics and someone will get you through it. Hope this helps. And welcome to our group!! Jade