It depends on whether you need a clever z-axis. Is your player *always* at the same height? Do you never want to introduce different heights in your map with the player moving up and down the 'hills'? Do you never want to have them walk under something? And walk back *over* that something?
If you can answer Yes to all of those, then you can simply draw all the floor tiles first, then your player / non-player objects, then your 'tall' tiles. And you draw from the left of your *screen* to the right of the *screen* (not map), working your way down to the bottom of the screen. That's a pretty naff explanation, and from memory too. There are several articles on gamedev - I picked all I know up from online articles...
The problem with thin at the bottom is if you have two tiles at different heights, with the taller one in front. Things get tricky as you approach the point of the tile 'nearest' you (in terms of you looking into the screen). Try to draw as many scenarios on paper as you can, and imagine how the player images will overlap around that.
If you can answer Yes to all of those, then you can simply draw all the floor tiles first, then your player / non-player objects, then your 'tall' tiles. And you draw from the left of your *screen* to the right of the *screen* (not map), working your way down to the bottom of the screen. That's a pretty naff explanation, and from memory too. There are several articles on gamedev - I picked all I know up from online articles...
The problem with thin at the bottom is if you have two tiles at different heights, with the taller one in front. Things get tricky as you approach the point of the tile 'nearest' you (in terms of you looking into the screen). Try to draw as many scenarios on paper as you can, and imagine how the player images will overlap around that.