I'm considering painting a standard narrow (12-24") wooden trellis in a bright color to grow a Clematis vine in our side yard. This spot has a south-east exposure with heat in summer, direct sun most of the day (until early afternoon), and (usually) winter rain. I'd like the paint to be durable enough to not require yearly re-painting.

I'm wondering if anyone can advise me about pre-treating the wood (e.g. sanding), type of paint, and use of a clear coat or something to preserve the paint and color year-round, and any lessons learned from experience.

Many thanks for any suggestions!