Stockopedia has a recent article entitled "7 Ways to Find Stock Ideas". At the bottom, they suggested using a watchlist. This is something that I have started recently wrt to my defensive portfolio. I believe that this idea has much more merit than is generally recognised. No-one missed what happened with Tesco, of course, but there are plenty of other companies that you hold, or would like to hold, where the usual Brownian motion (not a reference to a certain self-proclaimed world-saving ex-chancellor and Prime Minister) of the share price pushes it too low, or too high.
I'm developing my own bit of software that looks at price levels of a company I am interested, and flags up the cheap and the expensive. I'm also starting to use ADVN a lot more. They have an excellent price alerts page. If a company looks interesting to you, then why not set a price that you are interested in buying. I have 24 entries in my list - although some of them are sales, and some for testing purposes. Here's a sample of my buy prices: DNO (Domino Printing Sciences) at 440p, OPTS (Optos) at 160p, RR. (Rolls Royce) at 670p, TSCO (yes, that again) at 260p, VOD (Vodafone) at 148p.
Now, some of these numbers look a little unrealistic; but you never know. I think TSCO will prove to be too resilient to fall as far as 260p. I already have some TSCO, so there's little point in me setting a price near comparable levels. If I am to top up, then I want it to be in the absurd price range. VOD is at 173p, and its share price tends to trade in a narrow range. So setting a price of 148p looks like a stretch. On the other hand, its 52-week low was 156p.
I think that a watchlist also adds another important dimension: maintaining discipline. It is too easy to become carried away with one's own ideas, and rush to invest. A watchlist helps maintain an air of detachment.