The safe thing is to do flights where you intentionally encounter IMC but you can get out of it easily. So, e.g., fly into a cloud layer where you can stay as long as you want, but which you can exit vertically. That's the best way to do IFR / instrument flight practice.
Just picking a lousy day to fly could land you into some lousy conditions. If the base is OVC006 and the tops are FL200, and the 0C level is FL060 (say, a typical summer warm front situation) then you have a huge mass of muck which you won't get out of easily. If flying formally IFR, Eurocontrol flight plan, you have to do as ATC tell you and you thus have to have the escape route (from icing, embedded CBs etc) lined up all along the flight, and always keep it open as you go along so you don't get into a corner.
This in turn results in most real-world IFR GA flight being done in VMC; at least the enroute portion where one typically sits VMC on top in sunshine while the "VFR-ghetto" pilots are sweating it out scud running below the cloud.
It is a funny paradox that one does the absolutely ludicrously hardest possible training and collects the hardest bits of paper, just to do the easiest imaginable real flying, with ATC doing most of work, with seamless GPS RNAV navigation, with controlled airspace being irrelevant, with an implied IFR clearance for the whole route all the way to short final, with the safety of instrument approaches.... but that is how this old aviation business is set up. Plain old VFR is the hardest flying anyone can do - if one actually wants to go somewhere for real.