Weight is very important in Space Agency. If a rocket weighs too much, it won't be able get into orbit. Every time something is added to a rocket, its weight increases.
There are several ways to conserve fuel so that weight matters less, unless the progress to orbit made is under 57%.
Tricks to conserve fuel
- Turn off the first stage when it reaches maximum velocity and the boosters will keep going the rocket going (unless using Delta IV Heavy Boosters)
- Quickly keep tapping the engines during ascent will maintain velocity and save fuel.
- In space, using gravity assists when passing by a planet or star at faster than orbital speed. While direction is determined by a myriad of factors, no fuel is used-unless you have to avoid a planet.
- When outside circles of influence, the amount of fuel to decelerate is greater than what was used to accelerate the craft.