American Sign Language was great for my kiddo: it's not the same as "baby sign", it's a complete language with its own grammatical structure, etc. We combined ASL with verbal language to introduce kiddo to mostly Spanish, but also a bit of Italian & French
Preschool age, we went through the alphabet (& numbers, colors, etc.) by making up silly dances to go along with songs (song for letter A = the ants go marching 1 by 1) while collecting various things from outdoors & around the house that began with that sound (or had the specific number/color, etc.) & created a poster collage of those items into that shape (letter/number/color)
Lots of beanbag tossing games -- for numbers/math, alphabet/spelling, colors & shapes, even nutrition (Googled the food pyramid & requested free supplies from the gov't), etc....
We stamped out letters/numbers/words into the snow or mud & wrote them on the frosty windows, etc.
Since my kid *hated* sitting still for a picture book, we would dress up & act out chapter books instead
The kitchen & laundry room is a good place for learning, too!
We got *out* of the house: lots of FREE play time with friends was a must.
Once I realized she's kinesthetic, it slowly became easier to find the joy in teaching her