basically...
the main sax used in most of the sax solos youve heard will be the alto.
Your lucky as youve chosen a woodwind inst that has the same fingering throughout the main octaves. so easy to learn compared to clarinet and others
Learning bits n bobs:
1) learn to read music (Get lessons in this)
2) scales and arpeggios will aid your learning curve
3) mouth form (embouchure) is the key to sounding like a pro
4) a **** sax can be made to play a lot better with just a good mouthpeice ($60 off ebay for a yamaha) a good option if your jaw aches after 5 mins from a dud mouthpeice.
4.5) if your getting a lot of squeaks go a harder reed.
5) if your looking at buying a cheap horn there are some AWESOME chinese rip offs around, which some pros now choose to gig with for around $350. (seriously!!)
a review of them:
www.shwoodwind.co.uk/Reviews/Saxes/Alto/Chinese_alto.htma good horn for a cheap price is the "LARGO" which is mentioned in the above site. Ive played this and its just as good as a basic yamaha.
I now expect you to sound like this chap in 6 weeks from now: