In my post on Finding Great Tenants, Curtis asked were to put the signs.
If you are putting out hand written signs (the best for a property you are trying to get handled, we know because we tested it) for a property that you have available for rent/sale or if you are putting out preprinted signs (you can use hand written signs too, we tested it too and you get good results either way) to buy more properties you want to put them at the busiest intersections around your property. I place them on wire stakes so when someone is stopped at a light or stop sign my sign is right there for them to see. You can also put them up on telephone poles but the utility companies my quickly take them down. Use 18 X 24 inch signs.
Also, make sure you check with your local authorities to make sure putting out signs are OK. (My method of checking was to put them out and see if they called me. The technique nearly got me $45,000 in fines in a new city. Test it out with a few signs first then roll out a larger campaign. An 800 number keeps you anonymous too.) In one city the ordinance was that you could put them out Friday to Sunday. I went out at 12 midnight on Thursday night/Friday morning and then picked them up late on Sunday. This can be a good strategy to stay in good graces with the city. Most city workers don't work on the weekend so if you have them up from 6PM Friday to Sunday night you are in good shape.
Signs are by far the best way to get your phone ringing if you are either buying or selling a property. It is a lot of work but the payoff is worth it. You will only have to do it for a little while before you can outsource it to someone because you are making good money from all of the houses you are buying.