I begin every fishing trip to a new lake the same way. I sit in front of the computer and research the lake like crazy. I want to find out the color and clarity of the water, whether or not there are artificial fish cribs placed in the lake, natural fallen timber, where weed lines maybe, if there is an inlet or outlet on the lake, stocking info of all species. There is so much information that can be found online these days, but it can be hard to find and it certainly is not in one spot.
First things first, a simple Google search of the lake to view any lake associations, and a aerial map of the lake. In fact the aerial maps on Bing seem to be of a better quality at this time. Then I begin to search for a lake map. Be it from the DNR or a map manufacture a lake map is absolutely vital to successfully pulling up to a lake and catching the fish you want to catch.
Calling the state DNR is a great way to find information as well, though many states or under budgeted and you may find it hard to talk to someone who really knows anything about the lake or find that there has been no recent creel surveys or updates on the lake.
After obtaining as many lake maps as I can for the lake I wish to fish I start to browse the online forum sites to see if I can notice a pattern on where people have caught fish before. Now it is well know that you can not believe everything you read online, but after searching enough sites and pages you should begin to develop a pattern deciphering the truth from the bull. Forum sites are a great way to find out if there is any obvious landmarks that you may want to reference. Restaurants, bridges, islands are all things most likely listed in on the sites referring to where fish may be caught. The search button on forum pages are your best friend when looking for information from scratch. Also don't be afraid to ask questions on the websites. 90% of the folks that will answer you will do so in a civil manner and be genuinely will to help you, though you will have a few that you may want to ignore.
Calling bait shops can yield some results but that can be sketchy at times, bait shop owners tend to be nice folks when your in the store purchasing something, but while talking over the phone they may sound a bit, whats the word, rude.
You may want to try to talk to fishing guides if through your search it reveals there are some that fish your lake. They may not part with lots of info but they are always willing to talk.
Many times while during a search on one lake I find others that I may want to try or others that may be a better choice for a day on the lake.
Google the lake, look at all the forums you can and call anyone who may know something about the lake. Of course you won't know how the fishing really is until you step out onto the ice that day, with all the GPS coordinates in hand and auger ready to go.