I hate anything to do with painting and tend to leave my bikes "as found" but can do it perfectly well if I need to. Preparation is everything and cannot be rushed. I'd also recommend waiting for some of the mythical hot summer days as it is best done outside on warm, dry days unless you have a very good dry, warm, garage.
It depends on what you want to achieve with regards to what paints to use and how to apply them. Rattle cans can give a very good finish but I've found it can chip easily, as can car paints sprayed on. It will look great for a special occasion bike and you can lacquer over the transfers.
For an everyday practical bike, I'd brush paint it in quality enamel, with patience it will look really good and once it finally cures will be very durable. The most recent one I done was a Royal Mail Pashley which came to me FOC but in terrible condition. I'm very happy with the outcome but I put an awful lot of work into taking it back to bare metal (complicated by the fact that it appeared to have dozens of coats of paint applied over the years so it took a lot of time to strip it. Nitromers didn't help much, I used a wire brush in the drill (wear a mask). A blowtorch and scraper can be good too.
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Paintwork was in really poor condition and it needed re-painted simply to preserve the frame, otherwise I'd have left it alone (but I'm lazy!)
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I feel it turned out fine but it took a lot of work. Bare metal re-paint - I did my very best to get rid of all the rust but still treated it with Hammerite Kurust, then two coats of red oxide primer and and two top coats of a red enamel which I felt looked a reasonable match for RM red. It also takes ages for these types of paints to dry enough for the next coat. Where people go wrong I feel is applying the second coat too quickly and the brush marks the base coat and leaves deep brush marks.