Note that dpi is a printer capacity and printing is done by the magazine not you. As long as you have sufficient pixels for the required size, that is good enough. You should look at the quality of the pixels.
Capture the picture in RAW if you can, you keep more of the dynamic range than jpg. There is some debate as to whether 14bit RAW is any better than 12bit. The consensus is the that dynamic range is the same for both but you can extract a bit more underexposed detail with 14bit.
Modern sensors are good enough that lens quality makes a difference. Try and use the pro grade lenses or the better std ones rather than cheap kit zoom lenses. A decent macro and a wide aperture wideangle for interiors are handy. Unless you are seriously into wildlife, taking a big telephoto is a waste of space. Wildlife photography takes a trip all to itself. A good tripod, cable release and a flash that you can use off camera are all useful.
If you are going to take commercial photographs you have to start thinking commercially. Will this picture sell? You will have to adopt some commercial photographic cliches but avoid some of the arty amateur photographer cliches. Being original is really hard but the bike can get you to original points of view and give you the time to stop where a car-based photographer might not.
Good photography can take planning and time. You may want to stay at a location to catch the right light, or be at a public event at a particular time and place to capture action, eg closeups of a marching band getting kitted up rather than the usual distance shots of them marching past.
I've taken nice portraits of people I have met but have never sold them. There might be a market for creative portraits outside the studio, esp with things people value, eg craftsman working, farmers with their horses or tractors, family shots showing the house. You will need a mechanism to get good mounted prints to the client within a short time.