Are you talking overall proportions, angles, etc.? When I'm working on a design, I usually start with the sizes, proportions, angles, etc and then build appearance over that. (Actually, you can get from most good designs to a replica of almost anything you want that way.)

There are some fairly standard measurements... the aspect ratio of a sport plane wing (i.e., the proportionof its length (span) to its width (chord)), is usually between 5:1 and 6:1. The wing area tends to run around a hundred square inches higher than ten times the engine size (in cubic inches -- well, actually in hundredths of a cubic inch) rounded up to the next higher size.

So, If I wanted a 62" span trainer, it would probably have a chord of about 10" (using the rule-of-thumb aspect ratio) for an area of about 610 squinches (span times chord). That should take a .40 or .46 size engine (75cc). If I want ailerons, I can cut out about 10% of the wing chord for them... so they could be 1" or 1-1/4" aileron stock. The dihedral might be 5 degrees for a 3-channel plane (no ailerons) or half of that for the 4-channel version (with ailerons).

Balance the plane at 1/4 to 1/3 of the way beack the chord... I start at 28% just to pick a reasonable number in between.

The fuselage length will be a little over 3/4 of the span -- with around 3/4 of that behind the balance point and the rest ahead. So a length of maybe 46". The stab and elevator will be about a quarter of the wing span for 150 squinches (of which about a quarter is elevator)... the fin & rudder add up to a third of the size of the stab and elevator (and a third of that is rudder).

It's easy to start the design with a "semi-symmetrical" airfoil like the venerable NACA2412. (It's been with us for probably 70 years or more, but hold it up to the light withsome of the best of today's airfoil profiles and you'll be hard pressed to detect the difference.) Sitting such an airfoil flat on the wing saddle will give it a 2 degree positive incidence relative to a level referrence line the length of the plane. That ain't bad. Set the stab parallel to the referrence line and point the engine down two degrees and you have a pretty solid, well-proven setup.

There are a lot of articles around (including on the web) with recipes like this for a successful starting design -- they'll vary a little one from the other, but all will be simmilar. I think Howard Sullivan's R/C Dlight Unlimited sight has such an article and I know it's goit a lot of other great stuff... read it all. Most of what we do in the design arena is far from new, so there are many good references and lots of peolpe to give advice.