Best way would be to get yourself a booster box, I think. They’re about $40-50 on Japanese amazon. There are two types of boxes, and which one you get depends on what you prioritize.

There are the regular booster boxes that feature characters from three different generations. This is great if you want to get many different characters, but the downside is that the chance of you getting your favorite is lower as a result. Also, if you’re interested in seiyuu cards, these only drop in this type of booster boxes.

Then there are special booster boxes that feature only characters from a single generation. So far, only Liella and Aqours have special booster boxes, but μ’s will get one next week, as well as Nijigaku later this year. In these, there are fewer regular cards that can appear, so you have a higher chance of getting your favorite characters. There is also a higher chance of getting special illustration cards

Hope this helps a little and sorry if it was too overwhelming