I have never had that problem, but used Krylon mostly. Was your base coat/primer smooth to start? Is it humid? If so, that doesn't help. Good temp. is important.

Hopefully others will chime in.

Without seeing what you are looking at, perhaps you may have raised the wood grain a bit. Simply sand smooth and and re-prime and topcoat. If you want it to pop finish with a clear coat.

If it is something else show a pic, its all fixable.

your last coat should go on thick and consistent. Once the first few layers have dried I lay it on thick one last time. It allows to paint to pool and relax, creating a consistent surface. This really only works on horizontal surfaces as the paint would drip otherwise

I like to do three coats, all just a few minutes apart. First two are relatively light with the last one being a bit heavier and wetter. I'll have a surface done easily in ten minutes. I think the key is to make sure you're spraying away from the wet area, not into it. That keeps the overspray on the dry area.

Humidity...not good. I've seen it make paint turn into 'cotton-candy sugar' like finish...small bumps. Not sure if the problem, but could be a contributor.

Temp and humidity are a factor yes... But I think the manufacturer has more to do with drying time. (I use dupli color for the smooth actuator and quick drying times)
What I do is apply a light "tack coat", then wait 5 - 10 minutes, then spray a thicker full coverage coat. This should give you a smooth finish.
Practice of a scrap piece of wood. See what works best with the paint you have.

Here is a tip I have tried. Heating the contents of the can. The propellant makes the paint cooler than the surface to be painted. Hold and Shake the can of spray paint in the flow of hot water, from a tap. As you shake the can initially it will feel cold. Continue until the can does not feel cold. Then spray it while the contents are warm.

Use caution as high heat can be dangerous.

This is the method I use also, my father told me to warm the can that way the particles of paint come out finer? Don't know if this true, but my garage is always a little bit cooler then outside temps. So I always warm my cans in warm water, I do this for shaving also

sand between every coat. period.

I've gotten great results from rattlecans as people are describing, a couple medium coats with dry time between, then lots of dry time, fine sanding, and a final wet coat. even rattlecanned a buddy's camaro hood with several days dry time, color sanding and clearcoats over. not "perfect" but a whole lot better than before, and a whole lot better than he'd thought possible too, it's a technique thing and conditions (temp humidity) are a factor.

I use 400 grit for final touches.

400 for final? That's pretty aggressive.

I have always had good luck heating the can under the tap with hot water. Run it under for 5--10 minutes while shaking.

After shooting i have had great luck putting under a hot lamp to help bake it. For a cab i would use a halogen work light and try and get some hat into the curing paint.

It does sound like you are shooting a little too dry. Spray painting is really about being able to see the sheen of the layer as you put it down, ( it helps to be able to see the coat at an angle as you lay it down) and being able to blend the passes together so they become one coat not a series of passes. You need to be able to balance too much (it will run and not cure properly) and too little ( it will come out dry and you will be able to see the passes as distinct paths after it cures, and the finish will be flatter than it is supposed to be).

it takes practice....Keep trying on scrap, do test swatches. be methodical ( keep records in an effort to make things repeatable ). After a while it's a real pleasure to be able to lay out a nice coat.

I spray a coat let dry for 2-3 days then sand, tack rag then let dry again for 2-3 days. I do this 3 times so it will take me 2-3 weeks to paint something with rattle can enamel. But I'll tell you that that paint is COMPLETLY dry when I'm finished.

^^^^^!!!!

Waiting for the paint to fully dry is very important. Seemingly dry surfaces, if still wet, will stick together.