On the assumption that you're talking about covering with glass tissue and finishing resin:
My golden rules.
[*]Don't do it in the cold. But you need ventilation.[*]Sand the surfaces to perfection, use sanding sealer and get rid of any dust. Fill indentations and joins. The epoxy will find them otherwise.[*]Have plenty of elbow room. Have room to hang up the covered item and prepare the hangers FIRST. (pins and string work for me)[*]Use plastic drip mats and bench covers. (Builders polythene works great) I use digital kitchen scales for measuring. Wrap them in a clear plastic bag. Glass jars, Paper or polythene cups for mixing. Beware styrene cups...they dissolve in most resins. You will also know what weight you have added to the model.[*]Estimate the area to be covered, add 25% and use the resin manufacturers recommendation for area to be covered. Don't mix enough for the whole plane at one go![*]Have some general purpose thinners from an auto-factors ready in a jam (jelly?) jar. This stuff contains alcohol, xylene and toluene in some ratio or other (at least the stuff from CarPlan (Tetrasyl) does) and will thin epoxy. It will save your applicator brush and scissors. Short bristled brushes are better than long. A good quality applicator is a boon because it won't shed bristles so easily. I don't like foam pads.[*]Have a supply of latex gloves.[*]Use a credit card or similar to squeegee the surface after you've brushed on the epoxy, before you lay the glass. Catch the surplus. If you lay the glass and the weave is saturated immediately, there's too much resin. If you lay the glass and are not happy, take it off again and put a new piece on. have a spare piece ready "just in case". Don't fanny around because lumps and bumps will be a major pain once the epoxy's gone off.[*]I have a set of nail scissors that I use for trimming into corners. I've had them for years and they live in my toolkit. Essential addition to the shears used for bulk cutting.[*]Thin the epoxy, either with thinners or warmth for stippling in the top coat of resin. Most finishing resins are very thin anyway, so room heat is often sufficient. A combination of brush and card will keep the resin volume to that JUST required to fill the weave. You can tell when the weave is filled by the way it changes from matte to gloss.[*]Don't keep fiddling with it trying to find perfection whilst the epoxy is wet. You'll know what I mean if you try it.[*]Allow the stuff to go off completely before wet and dry rubbing down.[*]Paint to perfection[/list]Hope this was helpful