Jane Blundell My go to reference for all things color related. When in doubt, check her color comparison charts.
Inaturalist Thousands of reference photos of sea shells, insects, birds, etc. Some free to use but all are available to use as a reference.
https://www.facebook.com/groups/TheAccidentalWatercolorist Facebook page for obtaining critique and advice
Great paint and great information https://danielsmith.com/
When I buy supplies, I go back and forth between Dick Blick, Cheap Joes and Amazon. One or the others will be having a sale or the best deal. For paint tubes, Amazon is usually the cheapest.
https://www.dickblick.com/
https://www.cheapjoes.com/
Where I go to get (free!) clip art for this site – Pngwing
Business cards – the best! You can put up to a different image on the back of each card and really showcase your art. The cards are heavy and feel great in your hand but you do pay for this – $21 + postage for 50 cards right now – moo.com
Business cards and postcards – high quality at a decent price – PSPrint These guys are real printers. They will notify you if they notice a problem with your order and really do a great job at a decent price. Right now they are about $30 for 250 cards. Yes, only one image for the set and not the quality of Moo but I use both – the Moo cards to give to friends and people at parties and such and the PSprint cards to put out at shows and galleries. Yes, I know about Vista Print and have used them but there is a big difference in quality and service when you use a real printer.
Photo reproductions – Mpix This is a real photo lab and they take great care with every piece you have printed – but you pay for it. They have specials weekly like “30% off of canvas prints” but they are still on the high side.