Blocking is one of those things you could easily miss if you teach yourself how to knit or crochet on the internet, but blocking is an essential final stage to many projects. This is your opportunity to shape the piece, coaxing the fibers to go where you want them to go — you can lengthen sleeves a bit, straighten lines, soften curves.
For this mostly-alpaca afghan, I let it soak in water for a few minutes, squeezed it out gently, rolled it in a towel and squeezed out a bit more, and then laid it out on my interlocking blocking mats, using T-pins to get the lines where I wanted them to be. Blocking will give you a much more professional result, and it’s so quick and easy, there’s really no good reason not to do it. The hardest part is waiting for the yarn to dry, so you can unpin it and luxuriate in the gorgeousness of your final result.