You can remember the meaning of 吸血鬼 with this easy mnemonic:
You're a leech, as long as you're alive you'll keep breathing (吸) my air and keep sucking my blood (血), and even after you die and become a ghost (鬼), you'd come back to steal my money too!
Using mnemonics to remember the meaning of Chinese characters like can have an enormous impact on how long to learn Mandarin it takes.