IMO, the only practical way to send humans to Mars is with a large initial group, possibly 200 individuals, one way. Sending 7-8 astronauts on a round trip is pointless. It dramatically increases the energy requirements, limits the time on surface, and doesn’t really accomplish anything.
Start by sending orbiters capable of very high resolution imaging of the surface.
Send several large rovers to Mars to find the best place to start a colony. I suggest SUV sized rovers, capable of high speed travel, 10 meter deep core drilling, and onboard sample processing. I call these rovers Big AL.
Using information from the orbiters, land the rovers in the most promising areas. Once the rovers have found the best site, send robotic supply ships via the economy route and land them at that site. The robotic supply vessel hulls can be pre-fitted with electrical wiring, plumbing, and other fixtures so they can be used as habitats when emptied. Enough supply vessels should be sent to ensure sufficient habitats and supplies for the proposed colony size, and for at least 5 years.
Then send in the first 200 colonists. All these missions will be one way, maximizing the amount of cargo and people they can carry. The 200 colonists will cover every possible area of expertise, and all will be cross trained in at least two other areas, with additional general training.
The colony can be built by moving the cargo vessel/habitats into nearby ravines and interconnecting them. If no ravines are available, trenches can be dug into the surface. Supplies can temporarily be stored in tents on the surface. Included regolith moving machines or Big Al can be used to cover the habitats with sufficient regolith to shield inhabitants from radiation. Another option is to send a nuclear tunnel boring machine and bore into rocky hillsides or the walls of natural canyons. We might even get lucky and find networks of natural caves.