You want to make a good replica? Here's some tips,

What you need,

Some experience and skills at the game,
SimplePlanes, (duh)
The abaility to run more then 300-400 parts,
Patience.
A internet access
Luck

The replica process,

Now here is a very important thing, do NOTmake a replica of a type of plane made 1000 times before. Planes like the A-10 Thunderbolt, P-38 Lightning, or P-51 Mustang, are made way to often and your chance of getting your replica noticed drops rapidly. Try picking a more unique plane or build that people don't make often like the U-2 DragonLady, 2016 Dodge Charger, or British MK IV tank. Those are more original then adding to the feed of P-51's and A-10's that people no longer really care about.

Your replica does NOT need to be a plane. It can be a car, tank, boat, ect. In fact, if your replica is a Chevy Corvette over a A-10 then that is more likely to get noticed. Because personally I do not see as many replicas of anything else other then planes a lot of the time.

Now that you have your replica idea set up, put aside a few hours or so over a week or two because this will take awhile for the build to look decent. Next, pull up a bunch of pictures of the replica you want to make. Google images is a good start. Make sure you check the pictures while your working to make sure you didn't skip a detail or something. It's also a interesting detail to make the top speed, size, and weight is accurate to in real life. That could help get the build noticed.

Do not be afraid to ask for help, if your on mobile and need help with a scaled or XML modded part, just ask a PC user for help. It's a nice community and someone would be more then willing to help if you asked nicely. Okay, so now everything is perfect to your standards and your ready to upload. Make sure that you go and before uploading, do research about the replica. You can even copy/paste a few intresting paragraphs from Wikipedia as long as you give credit to Wikipedia if you do that. Make sure the description looks nice and professional, laveling the directions clearly. If you don't put in the effort making the description look nice like the build, people usually won't put in the effort to click 'upvote'.

Okay, it's done, it's uploaded and the description you spent typing is lookig nice. Make sure you got those upload screenshots in perfect positions to show it off nicely. If you want, you can even make a forum post teaser of you using the replica for whatever. Now sit back, enjoy the hard work you've put into it. Congrats! You've successfully made and uploaded a replica!

Hope this tutorial has helped.