1 If you buy something from a charity shop, pay double.
2 Carry stress balls to squeeze when you feel under pressure.
3 Use your umbrella with manners.
4 Buy your electricity from a supplier who uses only sustainable resources.
5 Give your Lottery money to a good cause (only 28p of every £1 you spend goes to charity).
7 Swich off your mobile phone before going into the cinema or theatre.
8 Tell someone their label's sticking out. Especially if you don't know them.
9 Stop yourself saying 'I'.
10 Bring birds into your life; get a bird-table, and make sure your cat has a bell around its neck.
12 Volunteer. Try www.idealist.org for ideas.
13 Make your own compost. Vegetable peelings, leftovers, garden waste, tea bags all do it.
14 If you're buying a car, consider the new breed of zero-emission vehicles.
15 Put a brick in your toilet's cistern to reduce the amount of water used in flushing.
18 Go out, don't stay in.
19 Write down the number of mistakes you make in one day, and aim to double it. It's the only way to learn.
20 Make a fuss. Don't let chatter about the 'death of ideology' mean you lose your passion. Take action on things you think are wrong or offensive. Complain. Participate. Get organised.
21 If you have any clothes you haven't worn for a year, give them away: to friends or relatives or charity shops.
22 Watch the film It's A Wonderful Life. As many times as possible.
23 Plant a tree. Put one in your garden, or a local communal space; go to www.treesforlife.org.uk/tfl.patfsyl.html and learn how.
24 Have a party for people in your street. Ask them to bring a picture of themselves as a baby, supply lots of booze and food; get out Twister if you're really getting on.
25 Ditch the gym and join a team instead.
26 Register as an organ donor. Details at www.argonet.co.uk/body 27 Listen to children as you listen to adults - give them as many rights as you give yourself.
28 Paint the outside of your house for the pleasure of those walking past (not just the inside for you).
29 Take responsibility for your problems; don't blame others.
30 Use small local shops.
31 Take a mug into work, instead of using Styrofoam cups. Campaign to abolish Third World debt - the new millennium's most pressing cause . Call Jubilee 2000 on 020-7739 1000 or go to www.jubilee2000uk.org to find out what you can do.
34 Don't backstab: be honest, but not bitchy, with your colleagues instead.
35 Go to non-Premier League football matches and show your support.
36 Learn a new language.
37 Do at least one cultural thing a week.
38 Get to know more about where you live. Go to www.upmystreet.com for property information, crime rates, local politics and education information.
39 Wear bright clothes once a week. It will cheer everyone up.
42 If you're a Christian, read the Koran. If you're a Muslim, read the Bible. And so on. If you're not at all religious, read all of them.
43 If you have the choice, travel by train, not plane.
44 If you live in Leeds, take part in the council's hugely successful Two-Plus Lane (motorists are allowed on certain roads only if they are carrying a passenger). If you don't live in Leeds, lobby your council to follow the Leeds example. To share a lift, look at www.freewheelers.co.uk/freewheelers - save energy and make new friends.
46 Join a LETS (Local Exchange Trading Scheme) in your area - in which people exchange goods or services with each other (for example, you plumb in my bath, and in return I'll weed your garden) without the need of money. Contact Letslink UK on www.letslinkuk.demon.co.uk or write to 54 Campbell Road, Southsea, Hampshire PO5 1RW, tel 01705 730639. Or try www.oneworld.org/ letslinklondon if you live in the capital.
47 If you want to invest money, do so with an ethical investment company. Contact the Ethical Investment Research Information Service (EIRIS) on 020-7840 5700.
48 Encourage children to become leaders. It will teach them to care for others.
49 Telephone someone you haven't seen for five years.
51 Buy two copies of the Guardian and give one to a non-Guardian-reading friend.
52 Have your ticket ready at the barrier.
53 Get email. Who'd have thought technology would bring us together?
54 Check out www.globalideasbank.org for lots of ideas about improving the world - add your own, and you could win £1,000.
55 Read your newspaper's international pages.
57 Don't talk in the cinema.
58 Dog owners: pick up their dirt. It may be disgusting, but think of the children.
59 If you made a charitable donation during 1999, Millennium Gift Aid could generate an extra 30% for the charity. Find out more on 0151-472 6038/6056.
60 Carry mints and go to the dentist; don't inflict bad breath on anyone.
61 Write letters of complaint.
62 Take a plant into your office. Or a packet of biscuits. Buy everyone tea.
63 Plant green plants in window boxes on the street-side of your home to help combat car pollution.
65 Eat together, and not in front of the telly.
66 Learn jokes. Start by memorising Tell Us A Joke, every Saturday right here in Guardian Weekend.
67 Ring your parents more often.
68 Listen to songs that make you feel at one with the world - John Lennon's Imagine, say. Or ones that make you stand up for yourself, such as Respect, by Aretha Franklin.
70 Sniff walnut essence, eat walnuts. No, really. Alternative therapists claim that it helps you break with your past.
71 Visit www.thehungersite.com once a day. Every time you click on to it, the site's sponsors pay for three cups of rice for people in famine areas.
72 Stop abusing traffic wardens. Hell, say hello to one. You could even say hello to a policeman (but don't snort afterwards).
73 Don't shout at children. Especially not your own.
74 Why don't you just turn off your television set and go and do something less boring instead.
75 Pray. Not neccessarily to God, just say a short prayer offering thanks at the end of each day.
76 Crouch down when you're talking to someone in a wheelchair; offer your arm to a blind person at a zebra crossing; take a drink from the bar over to someone with mobility problems without making a fuss about it.
77 Take a first-aid course.
79 Buy fleeces by Komodo from 100% recycled plastic bottles - from £60, call 020-7490 8101.
80 Make hay, not war.
81 Give blood. Call the National Blood Service on 0845 7711711 or go to www.bloodnet.nbs.nhs.uk 82 Adopt an elderly neighbour. Stop for a chat, keep an eye open for curtains left shut. They might even do some babysitting for you in return.
83 Write to elderly relatives.
84 Get rid of all the clutter in your workplace. And at home, too.
86 Shop from companies that have ethical investment policies; subscribe to Ethical Consumer magazine (0161-226 2929) or visit its website at www.ethicalconsumer.org 87 Don't be too obsessive about 'dry clean only' labels. Often, hand-washing in cool water can be just as effective, and cuts down on harmful cleaning chemicals.
88 Pretend that the speed limit is 20mph in urban areas. Drive slowly - don't be bullied by the impatient person in the vehicle behind you.
89 Don't put condoms, tampons or sanitary towels down the toilet; instead, wrap them up and put them in the bin. Otherwise, it's swimmers, surfers and the fish who get it.
90 Buy the Big Issue, but don't just give the seller money - stop for a chat.
92 Get more sleep, and don't drive when you're tired.
93 Keep a bowl of fruit on your desk at work.
94 Don't just visit museums and galleries; use their cafes and buy from their shops, too.
95 If you get to a public phone and it has a credit of 10p, make your call but add more money to leave a 10p credit for the next person.
96 Take time off when you're ill.
97 Risk ridicule - smile at strangers, talk to shop assistants.
98 Find out the names of the security guards, cleaners and canteen staff at your place of work. And use them.
99 If you see someone lost, show them the way.
100 Fill the world with love, laughter and joy. Go on. It's our millennium.