Welcome to FSM.
Feel free to ask away, there are many people here that will gladly assist you.
We all feel at times like that, thinking that we bit of more than we can chew. Luckily most mistakes on a Model can be rectified with a little extra work.
Works slow, take it easy and don't panick and you should be ok.
IMHO, too many modellers now are obsessed with getting to 100% right the first time and don't experiment enough.
I also think that too many people rely too much on advanced techniques and tools and thus tend to forget and use the basics.
You don't have to finish the whole model with the airbrush, use it for where others won't give you the desired result.
In some cases you cannot beat the results of the old and basic technqiues using a brush, etc.
Anyhuh, enjoy the Asylum(aka forum).