If you're interested in synth sound design, the best thing to do is pick one synth and learn it inside out. Whilst there are an enormous number of softsynths on the market and their architecture varies, many of the lessons you'll learn by focusing on that one synth can be applied to the others
If you like to produce sample packs, music, sounds or whatever, you need to know, that market is super competitive these days. Also it’s not easy to enter the good shops and make the connections, BUT you NEED to try and never give up if get rejected once.
Do not be afraid to work and do not whine when you've got too much work to do. Do not forget that there are many available job positions for, say, graphic designers / 2D artists / programmers, but there is usually only one for the composer. So if you have any kind of work as a composer – stick to it, always try giving 110% out of you and it will be paid off sooner or later!