Stars are a very useful form of currency in Tunnel Town, used to purchase rare bunnies and to speed up breeding between two bunnies on the Dance Floor. It's best not to waste them in large quantities, unless you have the kind of money to buy them. But, you should take advantage of the "Free Stars!" feature. Every 5 minutes, you can watch a short ad, and when it's finished, you will receive a star for free. It's not hard to get into the habit of watching ads frequently, to start saving up stars.
The most productive way to spend your stars is to use them to speed up mating, as opposed to buying bunnies. For example, if you're trying to get an Albino but keep getting Prairies and Chinchillies, you can use your stars to speed up the breeding, to start another mating attempt right away. It's a lot cheaper spending 1 star to speed up a Prairie and 3 to speed up a Chinchilly, than to use 2,500 all-together to get an Albino right away!
You can take even more advantage of the "Free Stars!" ad feature. You know how a Purple Carrot costs 3 stars and how it costs 1 star to plant it? Yeah. Also, Purple Carrots will make any level 1 bunny into a level 5 bunny after eating it, it's that good, and a great way to level your bunnies up to level 10 to complete goals and to make them more sufficient at mining and digging.
If a goal asks you to buy an item that you don't want, the best thing to do is to buy it either way, if you have enough gems. Once the goal is completed, you can then recycle the item. In the end, you'll receive more gems than what you had initially.
To get the best outcome from mining, it's best to put the bunnies of highest level and of quicker mining rates to work, such as Toucan, Chameleon, Miner 49'er, and Luck (find out more about mining rates on the Gems page). Level 10 Luck Bunnies are the best miners in the entire game, so it's best to use those to mine the better crystals, such as the white one.
Instead of buying a lot of beds and armchairs just to get your energy back, buy beanbags instead. You'll end up wasting a lot of gems on furniture that can only fit 1 bunny. The reason that beanbags are better is because they're cheaper, and you can fit 3 bunnies on a beanbag as opposed to just 1. They also have one of the quickest energy replenishing times for furniture you can unlock early in the game.
Another tip is to make a whole different other room for just beanbags and it will be the room for your bunnies to get back their energy, the other ones can be for decoration.
If you have an extra Dance Floor, or you're free to use the one you have, you can get more money quickly by breeding two of your valuable bunnies together, and then selling off the offspring. Valuable bunnies tend to be the ones that take the longest time to hatch, and the star tip will come in good handy for this one. Good combinations to use include Albino + Albino, and Angler + Angler, since these two bunnies sell for the most gems (50,000!)
Chances of Rarer Bunnies
Leveling up bunnies to level 5 or higher will increase the chances for breeding rarer bunnies. Purple Carrots are an essential for this, as they're great for leveling up bunnies fast.
Flooring or Wallpaper Goals
Whenever you get a quest that asks for you to use flooring or wallpaper a certain amount of times, you can complete them without spending anything! You can place any kind of wallpaper or flooring wherever you want, and then fill it with dirt afterwards. This will give you back the money spent to place the wallpaper/flooring for free! Repeat this until you've completed the goal.
As far as growing crops go, the most cost-efficient way to get energy and XP for your bunnies is to grow carrots repeatedly. It is not the must fun method, as it requires the most attention. There is no good alternative for bunny XP, but a good financial alternative for energy is strawberries, and for time, green pepper, radish, or green leaf lettuce.
Surprisingly, carrots are not the most efficient experience for level XP. They, at most, can provide 2 XP per minute while green leaf lettuce provide 4 XP per minute. Thus, green leaf lettuce is the best crop for level XP for time, while carrots are slightly better for money. If you want to buy your bunnies energy rather than grow it, carrots are by far the least expensive option, but also require much manual clicking and dragging. green pepper and strawberries are acceptable alternatives.
If you don't like searching around your burrow while wanting to do something at the same time, try to make your rooms bigger. It'll trap the bugs in one place based on how big the rooms around it are and the more closer the bug is to your room then the easier it is to tap on it while doing something else.
Do you ever just want to make a room that isn't connected to any other room but it won't let you? It's actually very easy to unconnect rooms, just dig out a room and then use the fill option to remove the tunnels that connect it to other rooms.
Of course, this wont work if your room is big enough to connect with some other room with either the bottom, left, right, or top of the room, you'll have to remove a row of room from either room if you want both of them to be rectangles.
Instead of having to wait until you complete those kind of goals, you should dig the parts around you burrow that don't happen to have furniture on top of them nor connect to rooms you actually want (you can still avoid confusing your rooms with each other by putting different wallpaper) then fill them to dig those parts again, it should work. The smaller the parts you are digging, then the more times you have to do it so make sure you have enough space, stick to the dirt layer too, the other layers tire your bunnies faster.