NOT EVERYONE you see with rented moving trucks are newlyweds hauling their wedding loot home. Some are Democrats leaving town or more Republicans coming. We were one of those newlyweds three years ago when we brought our gifts back from New York and Boston. Our parents paid for the rental so they could get their living rooms back:

We knew we needed to do something when we had finished loading our mini station wagon and only cleaned out half my mother's living room and hadn't even started on my mother-in-laws.

A small-size trailer turned out to be the answer. It was hitched onto our car and hooked up to our car directional lights by the rental truck people in Boston. We loaded it up and there was even room left over in the car to see out the back window. The doors of the trailer were closed tightly with wire and then with a lock -- both provided by the rental company.

When we made it to Washington we unloaded. The next day we brought the trailer to the same company's local office. An easy and cheap move and, we soon discovered, one of many more to come.

Packing yourself, renting the truck and driving to the new place has become more popular than ever. It's also easier than ever.

U-Haul -- the oldest truck and trailer rental company in the business -- will not only rent you a truck, but sell you the equipment to move with: boxes, ranging from book cartons ($1.05) to wardrobe boxes ($7.95); four different sizes of mattress covers; dolleys ($5 a day); furniture pads ($8 per dozen); locks ($3.95 and $4.95); tape ($2.50 and $3.25); and foam padding (2.95 per bundle). The equipment is not sold at every U-Haul rental place -- only at U-Haul Moving Centers (the larger shops). There are seven in the D.C. area: 1750 Baldensburg Rd. NE; 16 N. Henry St. and 5005 Duke St. in Alexandria; 1107 W. Broad St. and 2920 Gallows Rd. in Falls Church; 1017 Connecticut Ave. in Kensington; and 15141 Frederick Rd. in Rockville.

Like most truck rental companies, U-Haul rents its trucks for local, round-trip use and for long-distance, one-way use. Renting a truck round-trip costs $35 per day for a 12-footer plus 20 cents per mile; $50 a day for a 24-footer plus 25 cents per mile. The price rises according to the size truck. All truck rental companies spoken to charged their customers for gas.

One-way rentals depend on where you're going. Troy Ashton, office manager at U-Haul's regional office in Arlington, said that right now more trucks are leaving the D.C. area than are coming in. "A lot of our trucks are in Texas, New York and Ohio right now. So renting a truck here to go to those states is going to run you more than renting a truck, in say, Texas, to come here. We need trucks here, so the price goes down. Trucks are not needed in many of those areas so the price is high. However, this won't last forever. Within a couple of months the situation could be reversed."

A sample price right now for a 14-foot truck going one way from Washington to New York City is $125 for the truck, $15 for insurance and $40 for the refundable deposit. After 250 miles, 25 cents is charged per mile.

Besides providing the mover with the equipment necessary for moving, for a crew to help them pack or unload. This new U-Haul service costs about $12 a day per mover.

If you're really cutting corners, it'd be cheaper to invite a few people over for dinner, as one friend of mine does, feed them well, serve lots of beer and before desert suggest they "help with a few things."

It's a way of getting it all moved, even if the friendship does diminish somewhat. (What do you care? You're leaving town anyway, right?)

Neal Dittmar at Ryder Truck Rentals says their rates also vary from month to month. "It depends on supply and demand. Right now we have a lot of our trucks in Texas, but not many in California. It's cheaper to move to California than to Texas even though the distance is longer," he notes.

"As of this month, a 12-foot truck will cost you $200 to rent from here to New York City (plus tax), $18 for insurance covering the truck, $9 for an optional policy covering the driver, $100 for a refundable deposit and 25 cents beyond 264 miles," states Dittmar, who is Ryder's one-way administrator in Beltsville.

Ryder also sells moving equipment: 95 cents for a book box, $1.25 for a medium-size box, $3.25 for a double-thickness dish packing box and $6.50 for a wardrobe box.

Dittmar says that Ryder anticipates a large moving year in 1982. "During the past four to five years with the recession most people have stayed in their one- and two-bedroom apartments. But by next year we think people's incomes will rise and they will again be able to afford that new house or condo."

At King Rentals (100 N. Stonestreet Ave. in Rockville) employee Richard Bauman says they offer three different size trucks: an Econo-Line Ford Van costs $22 a day, 22 cents per mile; a 12-foot moving van, $25 a day, 25 cents per mile; and an 18-foot van, $35 a day, 28 cents per mile. King Rentals only rents for round trips. Bauman says they also rent some moving equipment including four-wheel and two-wheel dollies for $7.50 a day and furniture pads, $7.50 a day for a dozen.

Bauman adds that they don't sell or rent boxes, but he suggests that customers get boxes from local liquor stores. "They're sturdy, free and they're just the right size. People think that large boxes make for less trips when loading and unloading. This may be true -- but they also make for bad backs. The smaller, liquor boxes are much easier to carry -- especially for books."

Larry Cornwell of Arlington Truck Rental Inc. -- a branch of the Jartran truck rental company -- says that right now to rent a 16-foot costs $40 per day, 22 cents per mile plus gas. Arlington Truck Rental, 1030 N. Filmore St. in Arlington, sells boxes ranging from 85 cents to $5.95 (wardrobe box).They will also rent dollies for $5 per day.

Moving guides are available from the larger moving/rental companies such as U-Haul and Ryder, by calling their local offices. Some of their suggestions:

Large objects: Measure the size (up and down and around) before deciding on the size truck you need.

Books: Pack books flat so that the spines won't break and don't jam them in. Don't pack fragile items with books.

Appliances: Fasten down spring-mounted motors as in washing machines; pack loose pieces of stove, securing burners, elements and trays with tape. If you're taking your refrigerator, check with a local dealer to see if your brand can be laid down flat -- most can, but some can't. Give utility companies a few days notice to disconnect appliances.

Dishes: Wrap all breakables separately. Nest cups and bowls.Stand plates, saucers and platters on edge. Stuff dish towels into any "air pockets." Try to stay under 40 pounds per carton.

Furniture: If possible, remove legs from all tables or load tables on their tops, legs up -- being sure to protect surface with a blanket. Don't wrap lamp shades in newspaper -- the ink may smudge onto them.

Beds: Cover mattresses and box springs to keep them clean. Lash bed rails together with rope or tape.

Mirrors and Pictures: Cut cardboard slabs to fit over the glass, bind with tape and label "GLASS."

Leave all inflammables behind: cans of paint, alcohol, cleansing solvent, greasy rags or mops, lighter fluid and aerosol pressure caps.

Save all receipts connected with your move as they may be tax deductible.