I do most of my posting and commenting on my cracked up lg stylo3, haha, It's tricky but I just use steemit.com to compose, sometimes I'll just write in the notepad app thats already available on the phone. It's not too hard to add photos from your gallery, takes a looong time though. Editing images I usually use the pixart app. Over all, you get used to it pretty quickly but it really does take much longer to get a post out :)
Good luck!!