What would be really be a game changer in this regard is either a Space Elevator type system (which would be really difficult and expensive to build even if we did have suitable materials to do it) or a Reusable Single-Stage To Orbit rocket (even the mighty Starship rocket is two stages, so this is also very difficult to achieve).

As for actual travel in space, faster is better (both in the sense that it limits exposure to cosmic radiation and microgravity, two things proven harmful to human health; and also that it reduces the need to carry a large amount of provisions onboard for a long trip), so it helps for instance to have in-orbit refuelling capability (so you can actually use your rocket engine to propel you faster) or different engines such as nuclear propulsion engines that have better performance than existing chemical rockets.