Maiko are apprentice geishas. Whenever you see a young lady in the “geisha” costume they are most likely not a geisha, but maiko. Maiko usually have a more colorful arrangement of clothing than geishas. In Kyoto you can go and pay to get dressed up like a maiko and have your make-up and the photography done professionally.
Maiko and geiko (another term meaning “geisha” that Kyoto people use) are often seen at night strolling around Ponto-cho or Gion. They frequent bars and restaurants while accompanying their clients. Ponto-cho is a great area for night-life and it is a bit surreal walking into a bar to realize that there is a geisha at the counter.
If you want to get the full geisha experience I would suggest checking out a dance performace. Dance performances are only held at certain times, so you have to plan ahead. I found a pretty comprehensive list of Kyoto and Tokyo dances here.
Here is a link to a maiko dance I found on Youtube. I feel like seeing it live is a thousand times better.