I have two DDs and they are both in the Competitive Cheer team. Our town has a Recreation team and a Pop Warner team since they don't have official school cheerleader teams until high school. My DDs still had to try out for the comp team in the rec league and that's the one I know the most about and here it goes!
-Try-outs
Try-outs are in March. The girls have to be going into 3rd grade before they can try-out. They have 4-5 day practices prior to the try-out day where they learn a cheer and part of a routine with dance & tumbling/stunt. The day they try-out they are assigned times and try-out in groups of three. They are judged knowledge of dance, cheer, attitude (cheerful, loud, smiling, spark), tumbling skill (both DD have done cartwheel with a round off and cartwhell into a split & back hand walk-over). Parents are not allowed to be inside the gym and watch their DD perform. They are judged by judges that are certified by the State Cheer Association and not affiliated with our organization just to keep it fair. The girls are given a number and that's how they are known to the judges.
-Findout whether they made it
We're lucky that we find out whether they have made by e-mail instead of being posted in public. This past year it was decided to have teams no larger than 25-28 so not every girl that tried out made it.
-Fees
Since it's a town sponsored rec comp squad the fees are not that outrageous. It's $175 per DD. This fee is used for the registration fees at the competitions so we don't have pay registration fees at each competition. Last year we went to 8 competitions & 1 in-town exhibition.
I did have to pay to come see the competition and those entrance fee ranged between $5.00-10.00 per competition. We also had a couple of overnights, so if your team does that, you have to take into account hotel costs. We try and share suites - for example for the big competition in Wildwood, NJ we had 4 families in the Presidential Suite so it was only about $60 per family.
-Uniforms
Last fall I had to buy brand new unforms for both of my DDs and it ran about $375 when it was all said and done. That's the vest, skirt, mid-drift, lollies, 2 pairs of sneakers (practice sneaker & competition sneaker), jacket with their name on it, pajama pants that they wear into the competition with the team name. I'm hoping that this year I won't have to buy two uniforms since my youngest DD can wear her sister's from this fall but I will have to buy sneakers since their feet are growing like crazy

We were lucky that both of my DD got free team cheer bags a couple of years ago because now they are selling them for $25 instead.
-Other costs
We have to pay for the girls camp and practices at our local Cheer Academy which is an additional $450 per DD.
Please take into account any "souveniers" at the competitions, like t-shirts, and all the "junk" they sell at the competition including professional action photos which start $9.00 for a 4 x 6
I will say that my DD absolutely love cheering. They have made great friends and yes, I won't deny there is drama at times, but it has been a great experience for them. Our town is pretty big, we have 6 elementary schools, a 5th/6th Grade Intermediate school, and middle school. So being in cheer helps them when they go from the elementary into the intermediate school being able to know kids from the other elementary schools.
My eldest DD will be in 7th Grade next year and is already looking into trying out for the high school football cheer team. She's lucky that the Coach of the High School cheerleaders is one of her teachers at the Intemediate school so my DD already knows that she has to work on certain tumbling moves to make it into any of the HS cheer teams.
Good luck!