Some very good advice there.
Ben, I think it is important to bear in mind that GTs are very fickle and there is much that we do not understand about their habits.
That being said, both current and tide are clearly important factors. At sites I fish regularly, I can tell almost right away upon arrival if the current is right. As others have said look for strong currents pushing against structure (eg a headland) or between structure (eg two offshore rocks). Moon phases obviously have considerable effect on that and periods at or just after full and new moons are often the most productive.
Picking where GTs might be according to tide is I think more difficult, and is where local experience comes to the fore. For example, at two sites I fish a lot, one tends to only hold larger GTs either side of high tide. At another site nearby, the best chances of a large fish are on the tide change, especially the change from low tide to incoming water.
If you follow some of the basic guidelines in this discussion and remain patient, you ought to find some GTs. The very best of luck to you.