Any tips for keeping cats safe outdoors?

[Emma.Pie]

I have 2 male kittens(brothers). They are 4 months old. They have had all their inoculations and in 6 weeks they will be going in for 'the snip'. They are outdoor cats, from a small age all they've wanted to do is get outside. Luckily I have managed to contain them in our garden, which is safe and secure. I have, only once, taken them out into the street (on a harness).
However tonight they managed to jump the wall into our neighbours back garden, luckily my neighbour came out and handed the 2 kittens back over the wall. The problem I have is that sooner rather than later they will manage to roam out of my sight, and no doubt I will worry until they get back. But does anyone have any tips on how to keep them safe when they are out in the big bad world. I spoke to the vet this week and was told that they don't roam so much when they've had the snip, but that's not for another 6 weeks and keeping them indoors isn't really an option as I have a child who is always coming in and out of the back door.
Any tips would be greatly appreciated.

[anthony]

I have an outdoor cat and the best way to make them safe is to take them to the vet every year for a checkup and make shure they have there rabbies Lucimia and all ther other shots and they should be fine just make sure u get them in before dark!