just bottled first batch but keep having problems with my siphon. what am i doing wrong?can i start my siphon by mouth? not sure please help ???
You can start it by mouth, but that’s not very sanitary. Most people who bottle flat beer use a bottling bucket with a spigot at the bottom, so a siphon is not so much of an issue.
Can you start a siphon by mouth? – yes but, your mouth contains all sorts of nasties that are going imto a nutrient rich solution called wort, NOT recommended.
What are you doing wrong, since you are posting this I’ll guess something, but without knowing what you did it’s hard to say.
Try filling the siphon with water and then putting it into the wort so as to lose as little water as possible.
If you have a broken filler or racking cane you can cut it so you have 2 good ends (not jagged break) on a piece 6 to 8 inches long. Sanitize it. Assemble your cane and hose and put the cane in the wort. Insert the cane/ filler tubing into the hose, exhale the suck on the tubing, and start the siphon. Crimp the hose and remove the tubing. Rack the beer. Your mouth will never touch the hose or wort.
I think it is a good idea to get good at siphoning, but if you keep having problems, an Auto Siphon would be a good investment:
+1 on the racking cane/filler to suck start the siphon.
I have also heard of people who get really big bulbed turkey basters from the local chef/cooking store and start them that way.
In all cases, if I have attached tubing to a racking cane (cane in the beer, not for starting the siphon) I also use hose clamps on the tubing where it connects to the racking cane to make sure I have a good seal. I have had air leaks that cause me to lose sipohon.
Filling the tube with sanitizer or water and putting your thrumbs over the ends works well too, but I would recommend sanitizer over water and I usually glove my hands with rubber gloves that have been soaking in sanitizer for a few minutes to be sure they do not contaminate.
I used to use an Autosiphon, but I have gotten away from it over time. No real reason why, it works good, but since I have moved to using heat to sterilize my tubing and racking cane, the Autosiphon does not fit in any more.
Good luck!
And you can use the same bucket and spigot to ferment in- so you never have to siphon at all! I haven’t siphoned in 3 years. 
Totally irrelevant if one uses carboys.
For glass carboys, a person can use a cap, cane & tubing with a small amount (<5psi) of CO2 pressure to get flow started which also provides a nice blanket when racking. Just my 2-cents!
When you do this, do you rack from the bucket before adding priming sugar, or go straight to bottling from the one bucket?
What size tubing are you using, and what kind of racking cane? I’ve found that 3/8 on a plastic racking cane can have a loose fit and cause problems siphoning, but 1/4 is fine.
When bottling the beer goes into a fresh bucket to mix the sugar solution. All my fermenters can do double duty as bottling buckets. Should try mixing the sugar gently in the primary and see how that works.
I use an autosiphon. Works great, easy to clean, and cheap. ;D
I have been doing this often. A second cap and cane will let you rack into a carboy purged with CO2.
Here is a good write up with pictures. Some may recognize the author.
Remember too, that a basic siphon has to have a vent to atmosphere in the vessel
being drawn from, so that as the liquid exits, air can enter…
Not sure of your set up, but if you only have One opening that the racking cane is
inserted into, it will Not work…you need the other open port so air can enter.
I started many siphons of beer by mouth, but I would spritz my lips and mouth
with everclear prior to doing this… ;D. Now I give a +1 to the bucket/valve setup.
Auto siphon. Worth the $.
note to all…autosiphon…good raising the bucket real high better thanks for all your advice. 
+1. Bottling bucket & a Fermtech Bottle Filler ( http://www.midwestsupplies.com/fermtech-plastic-bottle-filler.html ) for $2.50 is the way to go. I like to turn my brew kettle up-side-down and set the bottling bucket on top. That way I can bottle on the counter top. (Getting too old to crawl around on the floor to bottle)