Taping off your trim is good. Then cut the entire room and then use a roller. Also use primer, especially for saturated colors. And last, but not least, lay drop cloths down. Or use old sheets or whatever you have on hand. Good luck.
This should help https://www.hometalk.com/866035/painting-101-tips-tricks-and-advice-for-perfectly-painted-walls
Mover everything to the center of the room or out. Lay down drop cloths to protect everything and the floor. Repair all holes with spackle. Prime the spots after sanding them. Paint the edges first. Use tape if you don't know how to cut it - a short handled angled brush makes it easy. Then paint the walls using a roller. Let it all dry for a few hours and repeat.
Test your paint well in advance. Test next to trim and carpet or flooring and on multiple walls. Look at it at various times throughout the day (morning, noon, night with lights on) to be SURE you like how it looks on your house and not just on the sample card!