OK for really new teams I will quickly explain the basics of how the team should be organised.
You need at least five players, more depending on how active you all can be. One of these players should be your main caller – someone who is happy directing the other players where to go, calling rotates, setting up strats as Terrorists etc. The other players need to listen to and follow the orders / advice of this caller for the team to run smoothly.
Next you want at least one strong AWPer in your team for maps when controlling a certain section of the map is crucial to winning. I would advise to never have more than 2 AWPers at a time, as this is both expensive and reduces your teams effectiveness when rushing / in cqc.
At the start of a round, players should not automatically buy up, they should wait for the caller to call either a buy round or an eco. In most cases it will be obvious whether you will be buying or ecoing, but it is good to wait a couple of seconds, just to account for things like weapons picked up from the previous round, or one team member dropping a weapon for another team member.
I would recommend you try and keep the same CT setups as this allows players to become familiar and comfortable in their roles, which is very important.
Your team should definitely go over some detailed strats on an empty server, so everyone knows what to do when a certain strat is called.
Ultimately the best teams are going to be the ones that have a solid, active lineup of 5 players – with 3-4 excellent riflers, and 1-2 excellent AWPers, and with a confident and competant caller – who practice together at least 3 or 4 times a week. Join as many cups / leagues / tournaments as you can feasibly handle, and just have fun and win and stuff.