I am a native English speaker, and as far as I know, my language has no words that end in a stressed h sound. So, I'm creating a conlang, and I thought about putting one at the end of a word, but I have no clue how to pronounce it without a vowel following it (in other words, not "ha", just "h"). Any advice? PS: In case it helps, this h would follow the IPA sound ӡ.
"Stress" is a property of syllables, not consonants, so you could drop the restriction "stressed". In fact, no words in English end in [h], leaving out spelling where it is an orthographic device to indicate something else. There are some languages with final h (Sundanese, Arabic, Somali and North Saami in one interpretation), but it isn't common across languages. Having words like [mæʒh] would be particularly challenging to pronounce, and if final [h] appeared only after [ʒ] then that smacks of misanalysis (like, why not just say it's a pronunciation feature of final /ʒ/?).
Arabic being a relatively widely-taught language, it might be best to "get the hang" of final h by practicing it in Arabic, and then transfer the skills to the conlang. The downside is that online teaching materials usually require you to read the script. Perhaps fdb knows of a pedagogical list of online final-h words with recordings.
A typical approach to pronouncing final consonants is adding a short Schwa
[ə] after it and then practicing with gradual shortening the vowel to the minimal possible length.
I have no academic books on this topic, but I have personal experience teaching my Thai friends how to pronounce English final consonants. In Thai language, a considerable amount of consonant sounds can't be final in the syllable, so average people have difficulty even with seemingly easy final
[s], or even voiced plosives
[b/d/g] — while, obviously, having no problem with these consonants as initial ones in the syllable.
This technique has helped me a lot.