if you begin to play it, you will never stop it.
Only white cards are worth points. White cards always display a number divisible by 3 - more precisely, the numbers on white cards are based on this formula:
2^k * 3 with k=0,…,11
Just a reminder: 2^0=1, so you get the following numbers for the first k's:
k=0: 3, k=1: 6, k=2: 12, k=3: 24 and so on until k=11: 6144
Now, when you run out of moves, the white cards are each scored and then added together. This part is a little confusing because they are not worth their number in points. Instead, the k from above is used to determine the point-value of each card as follows: If a card has the number 2^k * 3 on it, it will be worth 3^(k+1) points.
Play slowly and consider your moves - use the slow slide to see what tiles will match.
Focus on matching small tiles - don't let too many 1's and 2's build up.
If you're in a tight spot, don't always go for large matches straight away. Try to line up moves where you can clear multiple tiles at once and give yourself some free space.
Try not to get big clumps containing only 1's or 2's. Keep them spread around and you'll have more options.
Always assume that a white tile will be a 3. don't gamble on getting a higher number unless you're out of options.