You will get a million opinions...and more encouragement:

a) go for it
b) lights as much to be seen as to see
c) I your mtb has knobby tires and you are commuting on the road, going to smooth tread tires will be worth the investment.
d) if you have straight bars only, consider gettingn bar ends like the ergon or cane creek ergo
d) go as you learn and your budget allows.

I like bike specific clothes for longer commutes, especially bike shorts.... there is a reason for them, but clothing needs vary dependingn on climate, speed of commute, work place and a thousand other things.

I like clipless pedals or toe clips/straps