Hello, my diatonic harmonicas are also Lee Oskar, I mainly use the one in E but I also have in C and G (very low)
E is the highest I have, but I think if one day I buy another one it will be in A, just because I don't know why exactly but I've a feeling it can be nice :-)

As for the chromatic it is a Hohner Chrometta 14 holes, I prefer 14 holes (or 16) because you have 2 more holes in the low notes, and that can come handy in some tunes.

I've been playing by myself the harmonica for several years, nearly 10 now, it's not a dedicated work, but at some periods I play more often. Note that I try to always have an harmonica on me, if not the chromatic (my favorite) then the diatonic can be handy in one pocket, and I play it whenever I have time to waste, waiting for something or someone, or even when walking from point A to point B.
I know that playing while walking has been a good exercise for breathing and playing in rhythm with my feet, as to what people think of the sound, after many many many walks playing, I really don't care anymore, they only hear a small part and if it's good or bad doesn't matter to them or me.

Then for tips and tricks I'm afraid I can't help you, you know I have a big problem is that I can play ok with one note but I've never trained with the WHOLE MOUTH technique, called tongue blocking, so I'm limited in the sound I can produce, only precise melody one note at a time, that's something I should work on, but I said that to myself almost 5 years ago if not more.

Happy Harmonica!