I'm currently self teaching myself piano. I am doing quite well and am around grade 3-4 standard. I just wanted to know what you think are bad habits you can develop during playing the piano. I know I'm making progress ubt I don't know whether I'm picking up anything bad.

self learning piano?
that's so ambitious and independent.
*wided-eye*

Bad habits would include poor finger/hand/wrist/arm positions, clinging onto notes when playing legato, instead of passing smoothly from one note to the next (ie not picking up the previous note at the correct time) or even not joining notes properly in a legato, incorrect or poor use of pedal (if used), poor fingering technique - or not adhering to the fingering, poor thumb technique (especially when passing under in scale passages), uneven control and strength (or lack of) in fingers with uneven and bumpy playing. That's just a few I can think of for now...... And that's not including things like inconsistent pulse and counting, ie the reading problems, or the musical phrasing and expression...........

I did have keyboard lessons in primary school but after about year 6, didn't bother.
A lot of those sound familiar. I think I also have too much of a dominating right hand. I'm sure that's going to be a problem. Mainly I think my problems are hand control centred.

..poor use of staccato and technique...playing slurs incorrectly..expression is a big one..knowing when and how each hand(and sometimes, only a finger where necessary) should dominate.....
..yes, musical phrasing and how the piece should be articulated...
..trills
...rhythm...
e.t.c. e.t.c.

it is a very ambitious step that you are self teaching piano, but i think a teacher is extremely important to evaluate you and tell you what yor weak points are .