In my next project I will be using all this sensors:
Sound
Temperature/Humidity
Light
My idea is to measure all the values in a work place, office, classroom, shop, ...
But, I don't know which is the best way to make the structure of the device.
Some of the ideas I had was using a servo to take four values and then make the average or using a tripod.
If someone have experience with sensors or has done a similar project please reply
Do you mean that you want to mount them on a servo? Then put the servo on a tripod?
Yes, that's one of the possible solutions.
But, if I use a servo and three sensors which I already mentioned. Is it going to affect the power voltage ?
I'am using an Arduino Uno I have enough analog pins ?
I think that you're OK with the sensors. If you Add an LCD, then you may need extra power.
But what's the purpose of mounting those sensors on servo? This microphone is nearly omniderectional . What kind of measurements are you taking and what accuracy you require ?
The measurements that I'm taking are of temperature, humidity percentage, lux (light) and dB. With this sensors i don't think I can obtain a really good accuracy, but any tip to improve the accuracy will be great.
And about the idea that you propose: Without using a servo, which is the best way to develope this project ?
This doesn’t tell me much 
In my previous job, I used to do light and soud measurements in schools and offices for legal reasons and all tools to do that had to be certified and their serial number had to be put on a paper. As for measurements - i just walked arround the class holding a sensors on certail level abowe the floor ( 1.3 meters ) and taking 3 or 6 measurements , depending on class size. So we have to know , why are you taking those measurements to say what will be the best. But i thing bulding a handeld device will be the best and simplest option.
This is part of a research project i'm doing in my school. My idea is to measure all this values to create comfortable work places using the legislation in my country. For example: I'm measuring a class and I see that the light is under the minimum, in that case I can advice the staff of that school, and tell them: You should change the illumination.
My idea to make a similar work, as you do in your previous job but measuring all the values using one unique device
And if I build a handled device, this would require a battery and a datalog shield ? Which components I need ?
First , make shure that you cant use a device which is not certified . Someone can say " I don't believe you and your device because its not certified and calibrated" . This is very important. Handheld device could be powered by recharchable battery bank or from power adapter plugged to mains socket. Just make long enought cable . Ypu could take for example 4 measurements in defferent places, on different tables in a class and write results on a paper - so there's no need for data logger. As for sound - just place a microphone in front of the class and take measurement for, lets say one minute and thake an average. Temperature and humidity won't change verry quick so one measurement in the middle of the class is enought. Would be nice to have CO2 level measurements aswell . But calibrating such a device to give accurate and acceptable results will be a big challenge - so make sure u have a possibility to do that !
Do you think is better to show the results in a LCD Screen or in the Serial Monitor of the Arduino ?
And with one unique Arduino Uno I can plugged all this sensors right ?
Well, it depends on how you like to have your results . You can read them from LCD and write them on a paper, or you can send them to computer, which will run dedicated program to collect data and print it. But then you need to carry a laptop, write a software for it, have a cable connected to arduino and laptop or make a wireless link etc. It gets complicated and more expensive. And yes - you can connect those sensors to Arduino Uno. Get LCD shield - you'll have lcd and buttons ready to use. Or you can make a little pcb witch all the parts needed for LCD to run. Then, you'll need a profesionall devices measuring parameters you want, to calibrate your device to make shure that your 500lx IS 500lx or close enought 
If you decide to measure CO2 level aswell - I can advise Cosir sensors - they are dead easy to use, cheap enought and accurate. And they can measure temperature and humidity too
This could work as an LCD Shield ?
http://www.miniinthebox.com/es/lcd-1602-keypad-shield-para-arduino-white-on-retroiluminacion-de-la-pantalla-azul-201211270080082_p478917.html
Could you please recommend me a battery that fits into this project If never use one of those or I could also use a 9V adaptor.
And finally this project with the sensors, the battery and LCD Screen is it going to take a lot of time and skills ?
Yes, this will work. It will give you two lines of 16 characters each. And some buttons. As for battery - 9V battery won't last long. Better to use some li-po accu pack but I can't recomend any as I never used one. Makind sensors work Isn't werry difficult . But make them show correct values , calibrated to standard levels - it can be tricky.
Thank you, waski