We're big fans of the standard ScotchBlue painter's tape ($7.30, Amazon) for taping off trim and ceilings. For detailed work, like creating stripes or working around glass, FrogTape ($5.63, Amazon) creates a tighter seal around the edges.
Having a drop cloth will mean less clean up later. Use it to protect floors and furniture from drips of paint. Really, no matter how careful you are, there will be drips. Scotch Plastic Drop Cloth ($12.58, Blick) is a great temporary option – just crumple it up and dump it in the garbage when finished. If you think you'll be painting again the future, consider investing in Blue Hawk Canvas Drop Cloth ($21.98, Lowes). You can always use it to make a slipcover or curtains later. Another option is to buy a Kraft Paper Roll ($26, Uline) to protect your floors. The extra kraft paper has myriad uses!
One annoying thing about most paint trays is that you have to refill them repeatedly throughout the job. The clever thing abuot the Bercom Handy Paint Tray ($11.15, ThePaintStore.com) is that it fits an entire gallon of paint. Plus, it includes a magnetic brush holder and handle.
PAINT ROLLER & REFILLS
The trusty paint roller can make quick work of covering a large wall. Invest in a roller, like the Wooster 9 in. Sherlock Roller Frame ($8.47, Home Depot), and you'll have it forever. You'll only need to buy roller refills, like the Purdy White Dove Dralon Roller Covers ($13.48, Home Depot), for future paint jobs. For tight corners and smaller spaces, the Mini-Roller Tray Set ($2.00, ThePaintStore.com) is great for maneuverability.
You may be tempted to stand on top of a chair or table but the safest bet is to invest in a ladder. The Multiple Position 12 Step Aluminum Folding Ladder ($79.93, Amazon) is compact enough to store in a small space when not in use. With its adjustable heights, you can use it as a step ladder or regular size ladder.
After you're finished painting and the tape has all been ripped back off, you'll probably need to go back to do a little touch up. The MÅLA Paintbrush Set ($1.99, Ikea) will give you a few options for touch ups and detail work.
(Images: As credited above.)