On a spherical rotating world ocean currents are driven by the world's rotation. The explanation for this gets rather technical, dealing with inertia and relative rotations, but the effect the easy: All else being equal, currents flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. An ocean straddling the equator will have a major current at the equator heading from east to west and currents on its north and south boundaries heading from west to east.
Of course "all else being equal" is rarely the case. To accurately map currents you should begin with the largest water distance along a line of latitude. Keep in mind that once all that water starts flowing it has to go somewhere and you can map the lines of flow.
Your existing map looks pretty good. I might change some things, but currents can do some really strange things. (Particularly, that eastern flow above your western equatorial continent doesn't look right to me. I'd think the equatorial current to the west would tend to "pull" water out of that sea.)