I tend to make a list of the blocks, add a letter to each piece, then put the straight pin with that letter stuck to the pile it goes with. Lots of sticky notes also on fabrics I've decided to use for each piece and/or block. Seems to help me keep things straight as I go along especially if I have to push the project aside and work on something else for awhile, then go back to the 1st project. Just look at my note, find the alphabet pin the goes with it and go.