Firstly, drawing or printing if it's necessary the cutting line you proposed to cut. Some people think it wastes time and they can create the curves without drawing it before like they are painting, but, cutting curves is not just as simple as drawing. So be careful!
Secondly, you have to collect the right blade for your arc. A 14 inch in band saw is a nice size for cutting arc. There's a worthy notice for you that do not choose the blade with too many teeth because it'll be stuck very quickly by the saw dusts and becomes dull and over-heat.
Then, you need to set the tension and guides correctly. It's better to set the bearing-style guide close to the blade. Let's use the paper-thin gap in this situation. Space the guides over 0.001 inch from the blade's sides. If the guides stay far from the blade, it's hard to control the blade go along the curves. In fact, you had better under tension them.
Besides that, if your workpiece is large, you can use an extra table to help support your work.
Moreover, you shouldn't cut too close to the drawing line because you will not be able to fix it later. Cutting a curve is very difficult, and there's tough to cut it flawlessly in the first time. We all need to clean it, fix it later so do not cut too close to the line!
The cutting curve is always the most difficult technique of using a band saw. The tips above are just some recommended notes you need to notice when cutting curves. With each type of band saw machine, each type of curved shape, you need to find out the most suitable way to cut. Hope that these tips can help you to make a flawless cutting.
Source: band saw reviews and guides