Pixly editor is the best pixel editor on the play store. Download it here :

https://play.google.com/store/apps/details?id=com.meltinglogic.pixly

After specifying canvas size :

Step 1 : Toggle Transparency

Go to settings … color

.

note : scroll the menu to the left and right to view more options, denoted here by the green arrow

now toggle transparency

.

this will result in :

.

where the chequered background denotes transparency

Step 2 : Configuring grids

go to settings … view … configure grids

Step 3 : Creating a central axis

set cell width to image width / 2

set cell height to image height / 2

.

here i had a 32×32 image

you can also set the color

.

you will get those two red lines

.

you can also get smaller grids in line forms just add new grids or as dotted guides

.

be sure to pick another color if you want. it appears like where i set cell width and height to 1

.

you can view all your grids as such :

.

step 3 : enabling 2 views at the same time

it is very important t have a live view of the entire image independent of your zooming to refine your edits. see the mini panel. it is enabled by default :

.

in case you messed with the settings you can retrieve it with settings … view … toggle mini view

.

step 4 : color changing without palette

you can change lots of color settings in different formats without palette

.

.

changing light is extremely useful ! :

.

well, some basics to get you going !

note : the above was a real plugin i was working on. see the finished result :

view details at :

http://www.theotown.com/forum/viewtopic.php?f=70&t=4683&p=60095#p60095