I used the older Venus model, the original one. They’re all fine. And I also use the Satin Care gel by Gilette.
And you change the head (the part with the blade) when the blade gets dull.
Thank you! I understand now. I need to stop overdramatising on here and just trust myself. :s
I finally got one and looked for extra blades and it was so confusing! Two similar packets, just different numbers. What’s the difference between a cartridge and a blade? The lady working there was clueless as to the different in the boxes. They just had different numbers of cartridges.
lol, that’s the whole replaceable head part.
so the venus, I think, always have 3 blades… but you will get a box of 4 “cartridges” meaning 4 replacement heads… or 8 “cartridges” meaning 8 replacement heads.
You don’t need to worry about the “blades”. You just pop on the new cartridge on the top of the razor and throw out the old one. That’s it.
Oh, lol. Thank you. 
Hi:
I’d definitely go with the Venus Embrace with 5 blades over the older 3 blade model.
Alicia