Try to repeat these letters from youtube videos.
‘c’ is just an ‘s’, ‘ч’ is ‘ch’, ‘ц’ is a bit trickier than ‘ч’ because you might be unfamiliar with pronouncing ‘ts’ as a single sound and not just as ‘t’ and ‘s’. ‘ш/щ’ are the hardest consonants to learn because they sound very similar to one another and are essentially just hard/soft version of the same letter that was split into two separate ones, its best to hold off figuring them out until you get palatalization down.
Try to break long words down to syllables and pronounce them separately. Endings often make up 30% of the word and are pretty repetitive, so if you get those down pronouncing the whole word will be easy. Most scary long words are just two words in a trench coat, you just have to recognize them for what they are.
I’ve been learning chinese a little as a third language, i’m not far in it at all but it has been fun seeing random chinese comments and vaguely getting the idea of what they were talking about.
Also consider this your exam: pronounce защищающаяся (zashchishchayushchayasya) correctly. Unfortunately it is just one word without a trench coat.
Защищающаяся is kinda a meme word so don’t be intimidated from learning russian, there aren’t a lot of words like that. You can also leave the first ‘v’ in здравствуйте silent.