Whatever you do don't read the original book by Maria Montessori! She had some funny ideas, to be honest (HATED the middle classes, who are now the main devotees of her methods), but our experience of a DC in a Montessori nursery was very positive, and DH went to a Montessori infant school too.
The main principle is 'help me to help myself', which translates as: present them with something and see how they get on with it, if they ask for help or seem to need it them show them how it works, then retire to a safe distance and let them get on with discovering it themselves.
Some of the resources I can recall (all beautifully produced in naturally-coloured wood, of course, but you could easily make it yourself):
A rug or long piece of paper with squares numbered 1 to 10. Then you get loads of counters or pebbles or pieces of wood, and the kids have to put one piece on square number 1, 2 pieces on square number 2, etc.
A number board 10 x 10 from 1 to 100. Get counters numbered from 1 to 100. Yup, they then have to put the number 1 on square numbered 1, etc up to 100.
Shapes are big in Montessori. Most of what DH remembers from infant school has to do with triangles. What DD2 did with shapes was pricking them out with a pin. You get a shape on paper, then put a piece of paper underneath, and they mark out the shape so the paper underneath is just the holes. Is that at all clear, it's so hard to explain? Later at Montessori schools you have certain shapes and colours to represent verbs, nouns, adverbs etc.
Monerssori also seems to have a thing about the seasons (which are of course depicted as a circle) and continents. At least DD2's nursery did. There were wooden toys to represent the seasons in a circle too.
In a nursery environment it's also about them working together in small groups to 'solve problems' without adults - obviously that's a bit more dfficult if you're at home alone, but
The most amusing thing about Montessori was the absolute insistence that they could play with whatever toy was free in the room, but they had to put it back properly before getting another one out. Great principle. But then DD2 would come home and absolutely destroy her room after 8 hours at nursery. It's taken years to get her to develop a sense of personal responsibility for her own room at home rather than just scattering things on the floor, much longer than DD1 who didn't go to a Montessori nursery. No idea if that's just personality differences. But it's definitely worth going for it, without being overly dogmatic.