Before I proceed to the cutting table, I carefully study the pattern insert (the guideline sheets), making sure to
1. Study each pattern piece's shape as it is drawn on the first sheet. Often the grainline is noted on this drawing. This tells me whether I have any bias pieces to deal with. I highlight them with a little dot so I'll be aware of the placement.
2. Look at the list below the pattern pieces on the first page. I check off or highlight the pieces that I will use in my garment. I use a different color of checkmark or highlighter dot for the lining or the interfacings, since sometimes one of the garment's pieces will be re-used in the lining or interfacing layout. Sometimes, then, a pattern piece may have three little dots on it: one for the fashion fabric, one for the lining, and one for the interfacing.
2. Study the pattern layouts on the fabric, noting any unusual orientation or fabric folding requirement.
3. Read the pattern instructions from beginning to end, making little notes or highlighting something that I want to be sure not to miss. This is where I often change the sewing method or the sequence of garment assembly to best fit my fabric or my intended garment. I often substitute what I may consider a better sewing technique for the one that is described in the instructions. This just comes with experience and practice. I research anything that I don't understand and get the whole process clear in my mind before proceeding.
4. I count the number of pattern pieces that I will be using for the fashion fabric, the lining, the underlining, and the interfacing. I write that number down on the guidesheet, right by the pattern layout information. I always compare the respective number with the number of pattern pieces on my fabric before I cut.
Note: The pattern layout information always has a list of the pattern pieces to be used just above the layout picture. Sometimes, if I have made no design changes, I just check this list before I cut. Often, though, I may interface more or fewer pieces, or use more than one in a garment, for example. That's when I do my pattern piece number designation and count check extra carefully.