From High German...
First: Learn the correspondences High-alemanic / High German
- ptk are unvoiced unaspirated, it sounds like unvoiced bdg for a northern German
- k and ck shifted to ch in all positions
- n falls in all end-positions, not changing the vowel of the ending if it is an ending, elongating the vowel if it's in the stem.
- schwa is ä-like sound but in endings where it's -i
- No bavarian diphtonguasion (modern au, only the old au is there, otherwise uu)
- elision of -e- in monosyllabic prefixes, with assimilation before occlusives
- no early high German elongation of vowels in front of voiced occlusives
- rounded or unrounded phenomena depending on region (Basel unrounded, Zürich rounded, Skt Gallen rounded with vowel splitt etc.)
Second: Learn specifically Swiss German vocab and verb conjugation from two sources
- main media, more or less Zürich urban soft version, useful as all purpose language,
- your surroundings.
Third: introduce local specialties
- make sure you know the difference between niemer, nimmer and nümmer.
- short forms for verbs after fall of nasal consonant in stem or inherited from old short forms
- the -u endings in Wallis
- the vocalization of l in Bern German
- the aspirated occlusives in Graubünden/Grischun
- the declension patterns of your region
- and what ever you pick up around you...
When that's done, you take a holiday, you'll need it. And keep practicing when you come back from the beach.