When we see progress, and feel like we have spent the time well.
Please check out some of my original music and leave me a comment @ SoundCloud
(or in my profile!)

get some ideas shared and start writing songs... and a really good practice would be one with a few good songs.
actually playing our instruments...can't tell you how many times i've gotten together to jam with people and we play for like 10 minutes, somebody gets bored and gets on the computer and then it goes down from there to where theirs only me and the bassist still wanting to play.
Running through the old "established" set
Trying our hand at some new covers
Then a quick run through of our new selfpenned material

Added bonus points if our bassist doesn't break the mic during our synchronised headbang in Save it for the Bedroom. 3 weeks running!
Successful would be playing our set list all of the way through. A great practice would be learning more originals, though.
Success is maybe a new song, starting or finishing one

Running through some originals

Others but me writing lyircs, im rubbish at that bit

Jamming with my mates band who practice donw the hall

jamming different covers that we will never play live

Planning horrendus stage moves (chair surfing, piggy back guitar playing, how low can youi go while playing etc etc)
gettin all the originals done.. then playing master of puppets at the end
My Gear

Fender Deluxe Players Stratocaster
Marshall DSL 50 with 1960A
Quote by Jet_Black88
A successful band practice...

One where everyone shows up, ahahaha.

Rock In Peace, Ronnie James Dio

my gear:
Charvel Model 4
Custom Superstrat w/ DiMarzios (under construction)
Peavey Vypyr
saving up for a better amp
being able to play everything we worked on the day before at the beginning of practice, and have it very tight by the end. then maybe having one verse or chorus or hell even song come out of the jams.
Good practice is just planning to do something and kicking ass at it. Whether that be finish a new song, perfect old ones, or just review everything. A very very good practice is where we go in planning one thing, complete that, and then somehow do something else, such as write a new song in addition.
My Gear:
Peavey 6505+
Marshall 1960B
Schecter Hellraiser Avenger
Ibanez VBT700
Marshall Guv'nor
Marshall Echohead
Morley Tremonti Wah
Boss TU-2
Boss NS-2
Avatar 2x12
EHX Holy Grail Reverb
Furman SPB 8C
Boss Flange
After we play a song, we look at each other and go "Hell yeah, that was it!" That would be a successful band practice.
Quote by terryguitar

Quote by blynd_snyper
Ummm, petrol? Nip down to your local petrol station, buy a litre of the stuff and soak your balls in it, light them up and start playing with them.
we walked into practice yesterday and got every song right first try, and was very tight 2nd try. THAT was a good practice