How do I add more Delta V?

[SER187]

The only thing I know: boosters. If I could know more, it would help alot!

[Centauri0109]

Do a gravity turn at takeoff.

[Skorj]

In KSP having much more delta-V than the exhaust velocity of your engines (roughly 10x the ISP) is impractical. If you can't get delta-V up to 10x the ISP of your engines due to thrust-to-mass being too low, you need more or bigger engines.

Once you reach 10x ISP in delta-V, you're best off adding a new stage instead. With a well-designed rocket and an early turn after launch, you should be able to get to orbit, or nearly so, with one stage. But beyond that you need more stages. A stage with high thrust rockets to get started, and one or more stages with high vacuum ISP engines to take you farther.

[Paul Woods]

You add more delta V by shedding mass and using more efficient engines. You should try to make it so that, per stage, the wet mass is roughly 2.5 times the dry mass. You can also have radially attached fuel tanks that drain in order, allowing you to dump dead weight early and maximize delta V.

The easiest thing you can do to maximize delta v is to reduce your payload's mass as much as possible.

[Delle(DK)]

THere are several ways to get a higher Delta V ( more energy to go somewhere )

First of all you can do this with staging and decopule part of the rocket that is empty of fuel, you know just like they do in real life send up a big rocket and the higher it goes up the smaller the rocket get and in the end there is only the capsul with a few people and a little fuel left. The more you can decopule when it is no longer needed the better.
You dont always need a big fuel tank on your capsul it is just heavy to fly with and need more energy to speed up and slow down + the tank iself is heavy. So thinking about size is important.
But it become more and more difficult the more complex your mission is, since if you just want to go to the international space station then the above is okay and "easy". But when you want to go to the mum then you need something bigger OR refuel in orbit OR build your rocket larger. Alternative you can do like with the old apollo days where you have two vehicles docked together and where one return to earth while the other leave behind its gear on the moon and after that stay in orbit or is taken with you home and burn up in the atmosphere. But the most efficient and easy is to build one ship that can do everything itself from landing to taking off from the mum and before you take off it might be a good idea to dump some external fuel tanks to be as light as possible.
And you can when you return to kerbin save a bit on fuel to stop your ship by making sure you touch the atmosphere in 45km height and then the air resistance will slow you down for a few minuts before you are ejected up into space again.. and when you then fall around kerbin again then you will the next time again go down to 45km height and again loose speed for free.. And after you do this a few times you eventually have lost so much speed/energy that you you finaly fall down on kerbin.
Using the atmosphere to slow down is a delta V saving trick but can be dangerous.

But one way that give you more delta V is to launch in the correct direction and agle.
Basicly you want to launch east and at about 10km height be at 45 degree turn.
If you click T button and then on the small green prograde button then your rocket will pretty much fly itself into orbit in an okay way But stop your burn once you get to like 80km height and float up there.. Once you reach the navigation point wiht 80km height then your rocket need to be horisontal and again just follow the green prograde button path and then burn until your orbit on the other side of the planet is 80km as well
( everything above 70km and you are okay )

Regarding delta V yes you can strap on more boosters at launch and wait using your real engines.. Then the boosters can take you to example 10km height though much of the thick atmosphere. Boosters are a good way to get more delta V and decouple weight that is no longer needed.

You want to design your rocket so you use one kind of engines in the atmosphere and others in space.. Look for a place it say ISP that give you the efficiency in vacume and in atmosphere..
In space its good to have an efficient engine and you often have allot of time to burn and use it so you dont always have to go big.. I would say be most fuel efficient is more imporant and then you always install more than 1 engine.
But the larger ship you have the more complicated it gets.
In the kerbin system with mum and minmus you can build 1 rocket with 1 capsul and land and go home again.
But once you start to go further away then you might have to construct ships in orbit and refuel them in orbit before you want to go on long distant missions and dock sattelites and landers and rovers on one big ship.. OR send more than 1 ship to the other planet but it can be a little challenge to make them all arrive in the same orbit and inclination making it harder for them to example land the same spot on the surface or dock to each other in orbit.

[Rigor Mortis]

les fuel more engine. burn up as mutch as fuel in short time as possible then eject the dead weight

[Dalek1967]

This seems like a pretty open-ended question. What are you trying to do? Launch or interplanetary travel?