Hi! I wanna know any good warship there that is easy to do. I'm thinking about Revell USS Enterprise and Academy German U-Boat. Will it be an easy build? Is there a standard scale for all or most ships?

Shonen:
Depending on your budget there are a lot of good kits out there. Your higher end ones being Tamiya and Trumpeter.
The two most common scales are 1/350 and 1/700, but there are lot of scales out there too.
Panda had come out with a 1/350 Spruance destroyer I hear isn't too bad of a build and is easy on the wallet too. Revell has a 1/400 USS Enterprise that is a little steep on price, but I have heard mixed feelings on the build. (Maybe someone else can hime in on it)
Best thing I can tell you is to shop around and see what catches your eye.
Hope this helped
Paul

If you are looking at setting up a collection, 700 scale is the way to go. Pretty good mix of WW2 and modern. 350 scale has some gorgeous display kits. Those Tamiya battleship kits are great builds, look fantastic especially with a Gold Medal Models PE set. In your neck of the woods, you should be able to get one reasonably priced. Revell has a bunch of oddball scales of ships that are easy and should be fairly cheap

ever considered Airfix models? though they only produce 1:600 kits...i prefer 1:700 kits... i hmm..first time doing? find something that have less details and parts to fix, carriers actually are quite difficult for first timer. especially when fixing those AA.. #:-) how about trying a battleship HMS Hood by Tamiya or 1:600 kit by Airfic HMS Repulse?

For a first modern warship I would suggest the revell 1/470 Arizona. Nice lines and pretty much accurate with little modification to make it accurate. Using your current skills and learning new detail skills while you build her will produce a most satisfying replica. The price is a factor also. It can be picked up on ebay almost anytime for a few bucks. I've seen highly detailed ones go for several hundred dollars on ebay.

if you are looking for a 1/350 try the Tamiya Fletcher. Great first ship to build, not too expensive nor complexe so you can kinda get the hang of it before moving on to the big battleships.