Lets learn the easy ones first:
Remember EASY ONES First (PAM):
- Porifera - Sponges ( Porifera - Sounds like lot of pores.. similar to Sponge)
- Arthropoda - Ant, Spider, Cocroach, Prawn ( Arthropoda and Ant starts with 'A', also commonly seen together are Spiders and Cocroach). Also (Arthro) 'pod' means a home, and these 3 insects are commonly seen in home. 
- Mollusca - Mussels, Octopus, Snail  ( Mollusca and Mussles start with 'M' easy to connect with Snail and Octopus as all are living in sea ) 
Remember the FOUR WORMS - Tapeworm, Toungeworm, Earthworm, Filarial Worm:
Remember these 3 worms are examples of different sections:
- Tapeworm - Platyhelminthes:  Plates are washed from Tap water, hence they are related. Also Platy starts with 'Pla' same as 'Planaria' . 
- Tongueworm - Protochordata : Protocho sounds like Potato which we cook and eat. Hence tounge related with Protochordata. 
- Earthworm - Annelida : Imagine you had a pet earthworm named Annie. One day Annie died - 'Annie died' - Annelida :D
- Filarial worm - Nematodea : Remember 
- a. Filarial - fire a real 
- b. Nematodaea - new-man-today
- a + b = Fire a Real Man Today with Worm (yuk!)
 
Remember SEA :
 
Echinodermata - Sea cucumber, Sea Urchin - Remember as Sechinoderma if you like! Cucumber in Sea it'self is easy to remember!