Everyone will of course have a must have list. I will give you a short list off the top of my head......
Pots (my current favorites are clear plastic ones - some people prefer the solid plastic, but the clear are especially good for phals), media (as your collection grows you will probably find that you want to mix your own as you become petted to certain combinations - so perlite, coir, sphag moss, bark of different sizes, charcoal, etc.), fertilizer (specially formulated for orchids is easiest - and/or worm tea), white styrofoam pellets (of type that will not react with water - use for bottom of pots - provide good air circulation for roots), good scissor or small pruning shear for trimming (some will also add material for sterilizing them), mister (optional - needed or not some of us like to mist some of our plants with worm tea or other), bamboo skewers (for beginners to verify dampness inside pots deep down), trays filled with pebbles (for increasing humidity in the immediate vicinity of plants), insecticide (I use either bayer rose & flower - worm tea is a good organic non-toxic choice that works in many cases), fungicide (I've not needed but many do - especially if you have greenhouse environment), digital camera, and lots of time and patience!
Enjoy! mike