Changing the orbital inclination of an orbit is very energy intensive. But the people making that stuff happen have a few tricks up their sleeve to reduce the amount of energy (Δv to be precise) needed. It's a tradeoff between time and energy.
So the most obvious one is: Choose a launch site at the equator (or as close as possible). That's one of the benefits of systems like Virgin Orbit or stratolaunch because the plane can basically fly everywhere in the atmosphere. So they can launch directly at the equator (at least theoretically).
Another way to save propellant is to use a highly eccentric orbit with the apoapsis over the equator and do your correction burns at the highest point in the orbit (where you move the slowest).
If there are "tricks" to use the gravity of the moon and the sun to change your orbit towards an equatorial orbit "for free" (basically like sun-synchronous orbits the 98° inclination) I don't know. Maybe people with more knowledge about orbital mechanics can chime in here.
For GEO, Satellites are normally launched into a parking orbit with an apogee up at (or near) GEO and a much lower perigee. Most of the corrections are done in this mode before perigee is increased to a circular orbit as well.