An
MUA is a great addition to a shoot and can make for some great photos, but I'd suggest also having plenty of pics in your portfolio that were taken not using one. Reason being, on many shoots the photographer may not have the budget to hire an
MUA and will want to know what you look like with minimal makeup and/or with makeup that was done by yourself. In other words, they'll want to know what the "canvas" looks like before too many layers have been added.
But definitely try having an
MUA for a bit of fun, or if you don't feel confident in your makeup techniques - if nothing else than for them to show you ways to apply various styles of makeup. You can also find tutorials on YouTube etc. to show you some tips. Just make sure you don't rely on them for your portfolio and lead photographers to believe you can turn up to a shoot looking like you do in your photos if you're not able to recreate the looks they create. Good luck!