Transfer coins to a paper wallet created before the fork So I have a paper wallet with BTC (and I assume BCH) that I created before the hard fork. I have recently purchased some BTC and would like to transfer them to my paper wallet. Would this cause any problem or should I create a new BTC paper wallet?
Considering that you are transferring the new purchased BTC to the same paper wallet as you stored the earlier BTC, there won't be a problem at all.

Example:

You had 10 BTC before the fork in paper wallet with address 'abcd'

After fork you have 10 BTC in 'abcd' wallet in BTC Chain

And 10 BCC in 'abcd' wallet in BCC Chain

Now you buy 5 BTC after the fork and transfer it to 'abcd' wallet

So, now your final balance will be:

BTC: 15

BCC: 10

You can use these two balances separately depending on the chain you select.