How to move between objects in space has been studied since the 18th century.
The problem is known as ‘Lambert’s problem’, after Johann Heinrich Lambert, and was solved by Joseph-Louis Lagrange. It can be applied to transfers to the Moon, between spacecraft, or to the planets.
This tool calculates the transfer between any two of the so-called Terrestrial planets within our Solar System: Mercury, Venus, Earth, and Mars.
The tool characterises a transfer on any given start date, including transfer time, required energy, and directions, and allows the user to find optimal (less energy) transfers. These optimal transfers will typically look like a Hohmann transfer.
You can read more Nibbles in Space at 
SpaceProf.xyz 
. And, if you want to go into more depth at The International Handbook of Space Technology which is a definitive modern text on space technology with contributions from globally leading agency experts from NASA, ESA, JAXA, and CNES, as well as European and North American academics and industrialists. This comprehensive handbook provides an overview and a holistic understanding of the system-of-systems that is a modern spacecraft.