Sorry this is going to be a bit long, but do try to read it all if you can.
Receipts & bills, get a concertina fold wallet thing and label it up. Put the bills in when the arrive.
If you need to pay bills, have a section at the front that is just for that. Then as soon as you've paid them, move to the correct section.
Receipts I assume this is for stuff you have purchased that you need to keep them in case of returns etc. Use the back section and put them all in there. Once every 6 months or so, have a clear out of the ones you don't need anymore.
If the receipts are to reconcile your bank account, keep in a "bank" section of the folder and as soon as you have reconciled your statement, bin the ones you don't need and file the others in the "receipt" section.
Newspaper - chuck in the recycling as soon as you have finished it.
We have a bag in the corner of the kitchen and it all goes in there during the day and then out into the recycling dustbin at the end of the day.
Junk mail - same as newspapers. Look at it as soon as it arrives and chuck what you don't want/need. If you need to keep any of it, again have a section in your folder.
Children's drawings/paintings. Now I'm not sentimental about this, so keep a couple on the fridge and chuck them away after a month or two when new ones arrive.
Letters from school - keep in the concertina folder.
If, by cards, you mean ones you need to send - again the folder is your friend, for these. If you mean ones you want to keep that you have received, have a box somewhere to put them in (again I'm not sentimental about these and ditch them).
HOW TO START?
Start your new system with what comes in on the day you decide to begin. Then with all the stuff that "needs" sorting set yourself a target of 10 minutes per day or 10 pieces of paper per day. It is then not overwhelming and you will be able to accomplish it, rather than keep looking at it and not doing it because you're bored. If you can manage 10 minutes twice a day then it will only take half as long.
And, deal with it all as it arrives. it will only take a couple of minutes a day then.
Now, just so you know I'm not being a patronising bitch, I was horrendously disorganised and this system worked for me.
GOOD LUCK - YOU CAN DO IT !!