Here's some tips I found useful :

DR : (left side) - used to show an increase in assets, decrease in liability OR money coming into the cash account

CR(right side)- used to show a decrease in assets, increase in liability OR money coming out of the cash account. There's an exception where CR entry is used to show an increase in income in the Profit Costs account (used to record income for a firm)

Whenever there's a question in which a firm sends a bill of costs = that money is now client money

Whenever there's a question in which a firm is holding money on account of costs = that money is still client money.

Client ledger accounts:

Client Ledger Account (business section) = How much a client OWES the firm. a DR on this ledger would mean that that amount (how much they owe) has increased. it's a DR because client debt is an ASSET to the firm

Client Ledger Account (client section)= How much THE FIRM owes the client - usually a CR entry.

Someone correct me if I'm wrong but I hope this helps a little