I continuously use my credit card for my friends' expenses. Normally I could spend 20~30K USD each month to get more points/cash back. I don't have large credit limits so in most time I'll put cash into card first then spend money. I always fully pay my debts every month and normally use less than 30% of my credit limits.
Any problem with this approach? Will it become a bad record from the bank's perspective? Will it downgrade my credit score?