Have all the multipliers active at once by enabling the VM4TS9, VLWEN3, V84RYS, A72E1M, and VI3PS8 codes, which results in a x960 multiplier. One blue brick will give you a over a million points instead of a thousand.
Unlock the Treasure x2, Treasure x4, Treasure x6, Treasure x8, and Treasure x10 cheats in your extras menu, then activate them in order from highest to lowest to get a x3840 multiplier. A silver will be worth 20,000 studs each.
In any level, find the parcel and put it in the mailbox. A purple stud will appear every time you do so. Repeat this trick to get lots of studs quickly.