when pronounce "x" and "q",you should flat tongue.about"sh"and "ch",you should coil your tongue.you should make this practice:喜事（xi shi）and 汽车(qi che).if you practice this better,you can practice this word:出租车司机（chu zu che si ji）,first,you can speak slowly,and gradually you can speak faster.if you finished this practice,lastly,you can try this Tongue twisters：四是四（si shi si),十是十（shi shi shi），四十是四十（si shi shi si shi),十四是十四（shi si shi shi si).if you have problem,you can ask me.take care

What I tell my students: for the x, q, and j, your tongue should be in the front of your mouth, the tip touching the back of your bottom teeth, and the fleshy bit of your tongue behind the tip pressed against the roof of your mouth behind your top teeth. You make the sound by moving this fleshy bit to let air pass between your tongue and the roof of your mouth. For the sh, ch, and zh, it's the same three sounds, but your tongue is in the back of your mouth, pointing straight up at your palate, so they sound more rounded and don't lead naturally into an 'ee' sound Hope that helps.

I'm not an expert at all, but perhaps this could help you. Pinyin Sh and Ch are alveolar sounds. Pay attention, for example, to the position of your tongue when you pronounce the english "L". This sound is also alveolar. Place your tongue in the same initial position as when you pronounce "L", but say "sh". The "X" sound is very similar to the english "sh" (the position of the tongue is slightly different). Regarding the "ch" sound, as I told you before, it is also alveolar, so once again, to produce the sound, the tongue must be in the initial position explained before. So, with the tongue in this position, you try to pronounce the english "ch". The sound of "q" is very similar to the english "ch".

I'm a native speaker so I've never noticed the position of the tongue, sorry can't help you with that. But maybe you can ask someone to read 'xi', 'shi', 'qi' and 'chi' for you, the difference will be very obvious.

sada hq aithe rlh