Working within Roll20, my suggestion would be to add lines to the borders of your cliffs, and where transitions appear, that extend a bit beyond your square borders. Think of it like inking a comic. We can see what you have with the cells you placed and the shadows you have, but putting a border at the edge of the cliff will help define it. Since you are using everything squared off, alt + the draw square tool would probably allow you to accomplish this by making the cube essentially one thick line. Concerning grids, using them or not is up to you as GM. I frequently run with both on my maps. We just ended an arc in this town map for example: Setting the distances of the grid, sometimes its a good call to cut the grid and just use the measure tool to determine distance. In this one we still used the grid, but the edges tend to be "soft" as in there are frequently times where they don't line up exactly perfect with the grid (like around the edges of the houses or inside some of the rooms). Since grids in most games represent wonky sizes (like 5ft by 5ft) there is a degree of "squeeze" here thats up to the GM to allow or not depending on situation. It's pretty easy to get used to in time. I personally like setting distances entirely by the measure tool and letting players be much more organic about where they move and how their spells operate. Rules are just tools, after all, and generally grids were made as a way of simply allowing movement when measuring was too difficult to handle easily on tabletop. With Roll20 doing the lifting, I find it plus the move-and-tap-spacebar to indicate waypoints makes for much more interesting play on the table. Your miles may vary though!
