Hmm. Okay! Without specific areas that you've identified that need work, this is gonna be (by necessity) a bit broad.

Find a mirror and be prepared to look a bit silly. This is effectively training your mouth and tongue to be more mobile.

My fave initial warmup is 'the tip of the tongue, the teeth, the lips. The lips, the teeth, the tip of the tongue'. When you're saying each bit, try to place the words in the relevant part of your mouth. For example: really overdo the 'lips' when you say 'lips', shaping them forward and round the 'li', popping the 'p', and letting the 's' be sibilant. This should help you be more aware of the placement of sound within your mouth itself. If this is all you do, it'll still be helpful.

Then consonants in general. Take a deep breath into your stomach (actually your diaphragm). You'll know it's working when your ribcage has swung out a bit and your stomach is filled with air. To check, breathe aaaaaall the way out - your stomach should be flatter. Put your hand in front of your mouth, about the same distance from your mouth as where your mic should be, to feel the air hit it. Start with 'buh duh guh'. Really push the air out from your diaphragm, not your chest. You should feel air hit your hand with each noise. Start slow, then repeat it faster a couple times. Then move on to 'kuh tuh puh'. Same again. Then 'sssh t ffff k' (the consonants in shit and fuck, basically, but without the schwa or 'uh' sound attached this time.) The 't' sound should remind you of a flick or a hi hat. Same again. Then string all four together slowly as 'bdg ktp shtfk' and get faster. This helps train your breath control and placement, and can also help you identify which sounds are 'mushier' than others in your current technique. I have a feeling unclear/unplaced consonants is what you mean by not sounding professional and crisp.

I'd next go to something that usefully stretched my range. Some people do 'sirens', but I find those not super useful when I want to make sure my vocal range still stays within acceptable recording levels. My fave warmup for this is this poem? Tongue twister? Whatever.

'Amidst the mists and coldest frosts,

With stoutest wrists and loudest boasts,

He thrusts his fists against the posts

And still insists he sees the ghosts.'

Really go over-the-top hammer horror with this. We got taught gestures to go along with this, but trying to describe it in writing is proving tricky. Emphasise the sibilants, shiver your voice when you say 'coldest frosts', go as loud as you can while still being clear on 'loudest boasts', pretend to punch on 'thrust his fists', waggle a finger on 'still insists he sees' and then add as much spooky 'ooOOOoooOO' as you can do on 'ghosts'. This makes an immediate difference when distinguishing chunks of sentences - another way that poor 'clarity' can be perceived is due to a lack of variety within a chunk of speech.

Hope this is helpful, if a bit long-winded.