According to your plant and target of you expement, you should select

the type of inductiction media (semi solid)

the explant

hormones

then using well sterilized equipment you put the explant to the media and let them in dark for 3-4 weeks

after you have a caluus you can transfere a suitable peices to new media (with the same contents of induction medium or with new contents)

after sub-culture you can make cell suspension (agar free medium) which need aggitation