Tailoring? What can I expect to be done?

[Great Satchmo]

I've never really taken clothes to a tailor other than an occasional hemming of pants.

I've found that I'm very, very particular about the fit of dress shirt and so far the only affordable brands that have that fit seem to be H&M and the ilk, and their mediums are a bit tight in the neck and short in the sleeve to be real dress shirts (although fine for going out).

I have a handful of dress shirts that I would like to wear but are so large around the torso I can't get myself to wear them.

What can I expect from tailors? What type of alteration can they do and what kind of prices should I expect?

 

[Great Satchmo]

Same goes for blazers or topcoats?

 

[stefifofum]

As someone who's just starting to get things tailored, I'll second the request for a Tailoring 101 thread, if any of you sages are willing to share. (Or, of course, if anyone could point to an existing thread... Never saw any in my lurking/searching.)