Every installation requires a clean, flat, surface for the new product.  Scrape the surface, removing any residue and sweep with a fine dust broom or vacuum entire surface.  If you do damp mop or use any cleaners or solvents, make sure to let the floor dry completely before proceeding.  Fill any holes, cracks, and uneven areas with a filler suitable for your sub floor type.

You will have to undercut any doorjambs or protrusions that you can not put molding or transitions on.  Any places that will get transitions (any place that the new floor meets carpet, tile, metal door jambs etc) you will need to make a line on the floor 1/4" wider than the transition molding bottom.  Consider this line the mark to cut your new flooring to.  Using a scrap of pad and wood, use an undercut jamb saw to remove the jamb or protrusion.

Install the pad in lengths from wall to wall, trimming around all protrusions with a utility knife.  Make sure the pad is cut close to the the wall and lays flat.  Pad types vary, but most will have marks to indicate which side goes down.  If your pad is not marked, the solid plastic or foil side usually goes down because it is the vapor barrier.  If your have to splice two pieces together to make a complete length run, connect them by overlapping and cutting through both pieces to get a tight seam.  Tape them together as seen below.

Continue with the next row keeping it flat and butted up against the first edge.  Use masking tape or vinyl tape to secure the two edges.  Some pads come with a adhesive strip and top and bottom flap to connect the edges, place the bottom flap under the edge, pull the adhesive tape off and press top flap into adhesive.  If you have any holes or tears, tape them closed.

You will need a Tongue & Groove adhesive that you can get at most hardware or home improvement stores.  Check you instructions to see if they require a specific adhesive.  Usually you can use most brands.  The bottles are quart size and are designed with a special tip to allow you to easily place an even bead in the length and width groove. The bead should be placed on the finish inside edge of the groove and be the size of the tip opening hole.

It takes a little practice to hold the board and run a steady bead down the length and width.  By doing it this way, gravity will let the bead settle to the bottom of the groove and when the boards are pushed together, the adhesive makes an even bond, top and bottom.  If any excess pools, or gets on the surface, simply wipe it off before it dries.  After a few boards, you will see how the tip rests and slides easily down the groove.

You need to lay the first row along the entire length of the starting wall and connect the ends and push them against the wall so the width and length tongues are away from the walls, without gluing or spacers.  If the wall is uneven, the boards do not fit tightly, you need to use a compass or dividers and scribe the entire length of the wall and cut.  The piece that comes off last cut can be saved and used for starting piece if it is over 8" long.

Begin setting the first piece by using the appropriate sized spacer (check your instructions for requirements) putting one on the width end, and one every foot along the length.  Glue only the width groove of the next piece and slide it evenly into the first tongue, keep the width edges even.  Continue this process, spacing every foot to the end, and then wedge a spacer in the last end width.

You will repeat the process for the next three rows spacing at the width ends, always making the last spacer tight.  Use the cut off pieces as starters if they are over 8" and create a stagger for the first four rows.  At this point you should use some boxes of the wood and carefully press them against the entire edge of the last row to keep the rows from separating, and allow this part to dry.

Most quality engineered woods fit together with very little effort and form a snug tight fit.  If you need a little extra effort, you can use a tapping block that fits over the tongue against the finish edge, (never tap against the tongue) and gently tap into place with a rubber mallet.  The key is gently, excessive force will damage the wood.  If it needs more than a gentle tap, there may be a problem with the product and you need to contact the supplier.

When the first rows are dry, you continue the same process across the entire width of the area.  Note that most installations look best with a very random stagger.  The easiest way to achieve this is by using the pieces left from the end cuts as starters for the next row.  Trim as needed to keep each row starting piece a little longer or shorter, always keeping a minimum 8" space from the previous width end.  This will create a great random look and save on wasted material.  Trim and fit the last row, wedging it with spacers and let the floor dry.

Once the floor is dry, (usually 24 hours) you can install the base molding and transitions.  Using construction adhesive, fill the space and press the transition into the adhesive.  Carefully lift the transition and make sure the adhesive is adequate down the entire length.  Press the transition down again, and tape or weight down till dry.  Remove any excess adhesive.  Once the transitions are dry, your done.