Best tips for playing Candy Crush

My best tips in addition to those stated are:

1. Don't hold on to a win streak at all cost. It can be costly if you are nowhere near and chances are on your second attempt you will get an easier board. Don't pay more than 10 gold for extra moves, so if you can't definitely pass with 5 more moves wait until the game offers you enough extra moves for your 10 gold. If you do, you will get your win streak back soon enough as the next levels are likely to be easy. 
2. legendary levels: Play starting boosters on your first attempt only. If the game won't let you pass with these then you will be held up for a long time, so don't waste any more boosters until you find you get close. Watch out for any sign of a lucky board: dropping the right candies to make the matches you need to make, then take advantage of every opportunity the game gives you. If no opportunities show up, you might as well quit and try again, don't waste your boosters on these levels! 
3. Use events in the game to collect boosters. Then use your boosters wisely: your UFOs and lollipops are best kept to use before your last turn in a tricky level, use them only when you can see you can definitely pass if you play it. Hand switches are great to bring two colour bombs side by side on a starting board (e.g. in legendary levels when you are on a win streak and play starting boosters)

And here my tips for absolute beginners:

On levels 0 to 200 don't spend any of the gold the game gives you and save up all your boosters as well. If you fail a level, try again and it may get easy to pass on your second or subsequent attempt. Understand that the candies don't fall randomly but are controlled by the game mechanics and at each attempt it is different. So if the game leaves you one candy short, next time it may let you pass. Don't pay gold or use lollipops to beat levels 0-200! Be patient and wait for the lucky board, which will come eventually. From level 200-300 there will be levels where you will need boosters or gold to pass, so keep them safe for those "horrible 200s".

You can win gold in the episode races. Ignore the other players as they are just recordings picked by King. The event has a timer and mostly if you finish an episode the same day you started it you will win.

I'll add another of my tips here:

Don't fall for the tricks the game plays! Always be aware that candies do NOT drop at random near the end of a tricky level. King's algorithms decide if you get a chance to pass or fail. This early level is a prime example to illustrate:

Level 35, which looks like this:

By this time as a new player I have 50 gold bars and been given some lollipop hammers and fishes. On my first attempt the game gives me an easy board if I follow the hints and I am almost there with 10 moves left:

So I have ten moves to line up two more green candies to make the winning match here. So you think it is happening? Or maybe that I get the chance to get a colour bomb? So few colours, such an easy board. But think again…

They wanted me to use one of my lollipops or 10 of my precious gold.

The same trick the game plays again and again, often on our first attempt. The only difference being that on level 35 of course I passed easily on my second attempt. If you are at a level in the thousands, especially if it's a legendary or nightmarish level, then DO use that lollipop if you are in this position, as it may be many many attempts before the game lets you pass.