Well, it is already understood that even the most adept persons will make mistakes in a recital. That's why there exist the so-called Kshamapana Stotras (prayers that ask for forgiveness for mistakes committed during recitals).
It is customary to recite one such Stotra at the end of any recital.
Here is one such Stotra: https://www.indiadivine.org/content/files/file/209-kshama-prarthana-in-sanskrit-with-english-translation-pdf/
In case of a Stotra recital it does not matter much because it is more of a devotional practice rather than a technical or a ritualistic one. Even if you make some mistakes, which everyone will do, the deity will forgive them.
But if you are still too concerned about your pronunciation mistakes then you can chant the following verses (after you have finished reciting Shiva Mahima Stotram) from the Kshama Prarthana Stotram given above:
Yada akshara pada bhrastam matra hinam tu yad bhavet |
Tad sarvam kshamyatam deva narayana namostute ||
Prostrations to You, O Lord Narayana. Forgive me for all the mistakes
in letter or phrase or for any phonetic aberration that may have
occurred in my chanting.
Visarga bindu matrani pada padaksharani cha |
Nyunani chatiriktani kshamsva sa iswara ||
Forgive me, Oh! Sayeeswara, for any mistake in my pronunciation (of
visarga (:), bindu (a)or intonation of alphabet, word or phrase and
any other mistakes.
Aparadha sahasrani kriyante har nisham maya |
dasho yamiti mam matva kshamsva sa iswara ||
Oh Sayeeswara, considering me as Your servant, forgive the thousands
of sins committed by me through out the day and night
Also note that here Narayana is just an Upakalakshan. You can change the deity's name as per the situation. Since your prayer will be meant for Lord Shiva you can change simply Narayana to Parameswara.
Similar Stotras are also there which ask for forgiveness from Mother Goddess: What are the benefits of reciting Durga Saptashati Devi Aparadha Kshamapana Stotram?