What are you using for equipment?
Are your templates or patterns accurate?
Are you using a rotary cutter with ruler and mat?
Are you cutting with a scissor?
Did you wash your fabrics before cutting them? (There are those that are adamant that step is unnecessary - and there are those that are equally adamant that it is necessary) - but that could be another factor with the fabrics shrinking when you press them.
If your garment construction turned out okay - think about what you did "right" with that - and what skills can apply to the piecing process.
As others have suggested, if you can get someone to work with you - or for you to work with someone - maybe making the same block and comparing how each of you are doing something?