So, you want to get better scores and want them fast? Well let's start from the basics:
The safest yet easiest way to get shards early is to use this tactic shown in the picture below:
https://steamuserimages-a.akamaihd.net/ugc/796490743073543182/7AF6E6A0F3091D4A85ED061B3D5A6103D6D127DB/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

• 1- Bring swarm over to bomb and explode it
  
• 2- Go under the remaining swarm and collect shards
  
• 3- Find another bomb and repeat

After a couple thousand shards the swarm is too big and there is a chance of them crushing you from above, which is the main danger later in-game.

To survive, you must know the dangers and avoid them quickly. The main dangers are these:
Walls

• Walls are columns and rows of spikes formed together into a big wall. You start seeing them at around 1500-2500 shards but they don't pose any risk at all until around 5000 shards.
  When you start getting to around 6000 shards, the walls increase in layers. Before, you could just shoot a hole in the wall and go through, but later in-game the walls have so many layers, that they can trap you in faster than you can shoot a hole through, in which case the wall pushes you from in front and the swarm pushes you from behind and you die.
  Boo hoo, you're pathetic.
  Sadly the only way to avoid these walls is to avoid them even at the start of the game so your brain automatically associates walls with death and avoids them.
  The walls were the only thing that stopped me from reaching 10k points, until I learnt to learn their patterns and avoid them. Main trick with walls- If you see a hole and think you're gonna fit through there, you're very wrong. Triangle enemies always spawn in front of you and later in-game they spawn in big bunches, so while you're going through the hole a whole ♥♥♥♥♥♥♥♥ of triangles spawn in front of you, blocking you in and you die again. Lesson learnt.

Height changes

• It is very crucial to avoid very quick changes in direction later in-game and move smoothly, usually in a 8-pattern. If you suddenly fall to the floor, the swarm will start crushing you from above, leaving you no room to escape and you die. If you're still early in-game, you have a chance of surviving by shooting straight up and jumping as high as you can. Same goes for going up, so I recommend either going down only when there's a bomb on the ground or you're already on the ground.

One of the most efficient ways of staying alive is by jumping in circles. Sudden changes in height will slow down the swarm that's behind you and let you stay untouched. The only problem is that it only works when you're jumping around in mid-air. If you drop to the floor after running in mid-air,You Will Die.The horde that you kept behind you this whole time will now drop down at you crushing you from all directions, faster than you can kill them. The only way to avoid that is to drop down only when there is a bomb on the ground. When the swarm starts crushing you, touch off the bomb and they will all suddenly dissapear, giving you 2-3 seconds to collect the shards and keep on jumping. Rinse and repeat.

The other way is to do what you saw in the picture before, but with 1 and 2 switched.
When you touch off the bomb, you jump up above the swarm so that it can't crush you, fly behind it, drop and collect the shards, and escape from underneath them. Basically running vertical circles around the swarm.

Here is a list of things to always remind yourself when you're playing, which may dramatically increase your survivability.

• Shooting a bomb will stop it from moving and freeze it in place, so you can explode it without having to find where it is.
  
• The swarmers are faster than you, and if you move in a straight line you will die after they catch up to you.
  
• Run around swarms; jumping into a pile of swarmers to get a bomb is absolute suicide, 100% of the time. Two walls at 5000+ shards is enough to insta-kill you from both directions.
  
• The more shards you collect, the faster you shoot, which means you can cut holes in swarms easier and with less risk.
  
• Shooting at a bomb straight-on will make the bullets bounce behind you, clearing any swarms that may be close to killing you from behind.

I hope you found this quick and effortlessly-written guide somewhat useful. Wish you luck!
owo uwu owo -Toast