Word of warning - be very careful with acrylic yarns. They don't block particularly well, as they don't have 'memory', which is what is needed to block successfully (basically, the yarn 'remembers' where to sit in the garment); but if you press them you will remove all stretch, and can ruin the garment. This is particularly important on the rib of a jumper, which you want to be narrower than the body. If you press it, you will end up with a flared rib, which could spoil the garment, as it won't spring back into shape, even when washed again.
Blocking is important - particularly in lace patterns, which can go from looking like a string bag to a beautiful lace shawl.