So your project means you need two or more boards glued together to make a wide board and here is a method that can deliver that very easily. The video above is a demonstration of the process but I also want to talk you through the process.
In the example here I have two boards I want to glue up. As you can see, when the two boards are offered up no ammount of clamping will close the joint up. Therfore we need to impprove the fit.

Step 1:

I like to allow my boards to be a little longer and wider than the finished panel size. This gives me flexability and makes the job of joining much less stressful. As a rule of thumb add and extra 2" in length and 1/2" in width.

Whenever possible it's good to try and compliment the meeting edges of your boards by looking at how the grain matches up. You can skip that if the project is painted! Once you have your boards looking good add a face mark and some refernece marks that you can use to bring you back to the right spot. I used marker pen to add clarity for the video, normally a soft pencil is fine.

Now pick up the boards folding them outwards so the face marks are on the outside then secure them in the vice, just like the video. I like to use a handplane for shooting the boards. Don't let that frighten you! It's really not that bad. By securing the boards in the vice as I showed if the edge is planed a little out of square it makes no differnece as the edges compliment each other and stay dead flat when they meet up. For short boards a short plane will work, something like a #5 (this is the plane I use in the video and the plane shown in the front of the picture). Longer edges are more easily done with longer planes.

I set my plane a little coarse to start so I can remove stock quickly and get the edges close to what I need. A sharp handplane is essential, but if you follow the link that can be easy too. When planing try to hollow the the boards in their length. By trying to do this you will avoid making a hill shape and there is a limit to how hollow you can go as the sole of the plane stops you going to far. By having a slight hollow it also puts extra pressure on the ends of the joint during clamping. As a final step set the plane fine and take some full lenght shavings. Remove the stock from the vice and offer them together. Don't try and kid yourself, these need to go together with light pressure, if it's not right repeat the process.

Step 2:

When you are satisfied that the edge meet nicely it's time to add some glue. Do not be in a rush at this point! Also if you're gluing a few boards together don't get greedy, do your glue up in stages.

Get everyting you need ready. Have your clamps ready and set at the correct width and have your work area clean and tidy. The glue you choose is up to you. I'm using Titebond original for no other reason than I was given a sample pot and I can confirm it works well. There are many adhesives to choose from. Take advice from a supplier to make sure you have the best adhesive for the job in hand and you are aware of any safety issues. Some adhesives can be very toxic so do your research. Other adhesives may vary in their application, this method works fine for Titebond original glue.

Apply a generous bead of glue to the centre of one of the boards. Bring the edges together on the claps and give them a rub lighty forcing them together and getting them into postion to meet the reference marks. If you wish you can spread your glue with a brush or a spatula. Hower, the main photo is of the joint I rubbed, I pulled it apart so you could see the glue evenly covers both sides.

Once in the clamps apply the pressure lightly making sure the edges meet nicely and the joint comes up nice and snug. Don't apply crazy pressure to the joint. If you do you will force out too much glue and potentialy distort both panel and clamps. And indicator of sucsess is a gap free meeting edge with a nice little bit of squeeze out evenly along the whole lenght of the joint. I wipe my excess glue off, some prefer to wait until it is dry to remove.

On softer timbers you might need to protect the edges of your panel with packers. I find I don't often need to do this, adding too much clamping pressure to the point you damage the work can be a sign of a problem.

Once in the clamps follow the instructions on drying times given with your adhesive. Once dry remove from the clamps and avoid uisng the work for 24 hours to ensure the glue has fully set.

Step 3:

If your boards are long and you are working alone you might want to add some biscuits. These help you align the boards and are like an extra pair of hands. Don't go overboard and add loads, just a few to help you line up the boards. Also if you do use biscuits make sure you keep them in far enough from the ends. If they end up to close to the ends you risk exposing them when you trim the panel to length as shown in the photo.

Step 4:

All that is left to do is to give the panel final clean up. I chose to do that with a smoothing plane set very fine however a finish sander will also do a very good job.

I hope you enjoyed the instructable and thanks for reading and watching!