Alveolo-palatal consonants; palatalization is marked with an acute accent ◌́.
ITTL, Standard Chinese only palatalizes some consonants in front of the vowels /y/ and /i/ compared to OTL.
Palatalization would not usually be represented in maps, posters, etc, usually only for situations when pronunciation is important. Though in reality, palatalization would vary from speaker to speaker.
Generally look at the Wiktionary pages of characters: for example, you may except 京 (OTL jing) to be źing ITTL. However, looking at the Cantonese and Middle Chinese makes it clear that it is ging.
In common but not state-approved romanization:
Anglophone world: final -i may turn into -y, as in Zu Sugwey.
Batavophone world: ei might be spelled ij and ai might be spelled ÿ.
Retroflex consonants, which exist in OTL Mandarin, do not exist in TTL Standard Chinese. These are usually pronounced as their pure alveolar versions /tsʰ, ts, s/.
Sometimes in TTL Mandarin, -an reverts to the pre-modern Chinese and Cantonese -am. Check Wiktionary to see if this is applicable.
For example in 甘 (OTL Gan), the Gan is Gam in Cantonese and in the Middle Chinese reconstruction. Thus, it is Gam ITTL.
Erhua does not exist in the TTL Standard - er is usually replaced by ji in the formal standardization, though speakers with an erhua background might pronounce and write it with er anyways. Hokkien speakers may use ni.
In words starting with r like 人 (OTL ren), the r would be usually replaced with a j, giving jen.
Generally, u turns into w in finals, except for the exception right below.
Ao also turns into aw.
In Pinyin, the /y/ sound is represented by the digraph yu- & -ü- OTL, it is represented by y- or u- at the start of words, ü when it stands alone, and -u- in finals.