The ability to throw a dart accurately is down to "muscle memory" and muscle memory is something that gets developed through practice. Until the muscle memory has had time to develop it's generally recognised by industry experts that the easiest darts to throw are quite large in size.
I advise all newcomers to the sport to start off with brass darts. Brass being lighter than tungsten generally gives darts a larger shape which as said before is easier to throw with an untrained arm. Another advantage to buying brass darts is that they are significantly cheaper than tungsten. Many people start with brass and then jump straight onto the more expensive tungsten darts. This works out well for some players and not so well for others. The natural progression would be to move onto nickel silver darts. Nickel silver is a great in between dart for developing players. Being heavier than brass you can maintain your original darts weight and simultaneously reduce the size of your darts. This gentle change works better as your hand doesnt have to adapt too much to the smaller shape. Some people have jumped straight from brass to tungsten and found the darts just too small. The result is a set back that can take weeks or even months to adapt to.
Tungsten darts come in different grades They will start at 80% tungsten and typically go up to 95% tungsten. Tungstens high density gives it a much greater weight than its brass and nickel counterparts. The higher weight lends itself to developing much thinner barrels. The advantage to the thinner barrel are increased high scoring ability chiefly down to the small area taken up in the treble zones. Thin barreled darts tend to be favoured by advanced players.

Hi jasminemark, just read your three posts, why don't you go to the introductions forum and say hello to the guy's.

Interesting thoughts.........................

hi there! just to let you know that i use 22g darts but very recently was using 28g darts and used them
for many years! but one birthday bought myself some 22s and i score and hit the trebles and doubles so much
better but have always used heavy darts eversince i was a boy! all i can say is that there may summit
in that muscle memory talk!
Good questions keep them up!