Try to find area especially at park or reservoir area with overgrown weedy area as asa mentioned. Concentrate on flowering shrub where many flying insects are visible. Praying mantis are not easily seen, I use butterfly net, sweep the tall grass for stick mantis (they crawl on the net sometimes) and grass mantis (male usually fly when you do that), but it is probably stagmomantis sp you will be finding there, which can be found on small plant (usually sitting motionless on the leaves) not tree more than 10 feet tall. YOu may be able to find some adults now but most of the praying mantis are still nymphs so you might get a better chance coming across one next month or so.
