aspenhill said: Watering from the bottom is good. Another option is to use a mister.
You won't find a water can gentle enough that works for flats of seedlings- the droplets are too big, and dryer seed starting media around seedlings tends to 'lift-off' (float) as you top water, sometimes dislodging your seedlings- if you don't have a very fine spray.
I bottom water almost exclusively, but also use a misting nozzle attached to a hose. A misting nozzle is not to be confused with a spray bottle, which will be totally ineffective for your seedlings, as a misting bottle won't saturate the soil to any depth.
Also- to clarify- bottom watering IS NOT allowing seedlings to sit in trays of water constantly!
Allow them to soak up water from the bottom tray until soil is saturated, then remove them from the water and let the trays then drain.
Bottom water is my recommendation. You don't need expensive trays...
For years I've used an old plastic 'underbed' storage bin as my bottom watering tray.
Like this one- you might have several similar options lying around or pick up any kind of tray or storage bin at a second hand store.