If you are going to pin and you are having problems keeping everything straight, try pinning at a closer interval. If you are pinning at a 6" interval change to a 4" interval, it helps with bunching up. Also smooth as you roll the top on the roller and make sure that your edges of the top, stay lined up as you roll it on the roller. That way you know it's straight on the roller, and unwrinkled.
If you are going to baste the top to the backing and batting, do each as a separate operation, meaning get your backing on the rollers and then baste the batting to it, making sure that it's straight and hangs true. If you have side stretchers make sure that they are attached to the backing. Once you have that done, baste the top to the sandwich you have going, across the top. When I baste the top, I usually start in the upper left corner, I double check and make sure that everything is square and lines up correctly and tack the corner , and then slowly baste across the top edge, smoothing in front of the needle as I move across. When I get to the other corner. I come down the right edge again slowly smoothing out and down. When I get to the limit of my machine travel I tie off and go back to the left side and baste down and tie off.
There are a couple of ways to do the end of a row, depending on how you quilt. I work left to right, and usually start in the upper left corner of the quilting area, if I'm doing an edge to edge meander, I'll start and stop at basically the same place every time. If I start in the upper left corner I'll end in the lower left corner, so I can start the next pass where I left off on the last pass across the quilt. You can also just run your stitches into the area that the binding will cover and just stop, depending on the size of the quilt most people will never notice that you started and stopped.
The whole trick is to spend enough time making sure that everything is straight and lined up and smooth before you start, so it doesn't come back to bite you when you are too far into the quilt to fix it, without frogging it all out.