How to build a wooden picket fence?

I need the basics . There some picket fences that are lopsided like very uneven. I want my fence to be straight as possible and strong. What do i need?

Check the contour of the land ensure that the area that the fence is straight and check if there is an incline (like hill side)
build the fence in managable sections.Plant your two extream post, run a chord line to ensure that holes you'll be diging will be in one staright line. Choose an appropriate between distance each post.
Run you top and bottom and center boards from post to post, still using a chord line to ensure that is is levelled horizantally.
Cut each vertical picikett to the pattern u desire, then start nailing them on the horizantal boards. use a two by for piece of board to set the distance between each picikett to ensure uniformity.......Try That..U need a chord line /hammer nails and a 2x4 template

Drive a stake on each end of where the fence goes, then put a string on them and pull tight. now mark your holes for the poles dig and install the 8' sections to the posts, THEN add the concrete wet or dry and dirt using the string to keep it all straight

Go to Home Depot, they have free classes

I did home improvements for many years in the past but I would attend those free classes for tons of ideas.

Money, lots of money, and time, lots of time. The pre-made picket sections you can get at Home Depot are basically garbage. The wood is too thin and the pickets are held to the horizontal rails with tiny staples. To make your own you can do a lot better but it takes a lot of time and money.

I once made a 16' section ( two 8' sections) of picket fence to replace a part that rotted and fell down. I charged something over $300 for this. So, you figure $150 per 8' section instead of $50 at Home Depot and you get the picture. Here's the difference:

Home Depot fence: horizontal rails were 1x3; mine was 2x3.
Home Depot fence: pickets were 1/2" thick, mine were 3/4" thick.
Home Depot fence: each picket had 1 small staple going into each rail, or 2 small staples per picket; mine had two deck screws.
Home Depot fence: assembled unfinished; mine was painted two coats before assembly. (this prevents unfinished pieces from being overlapped where water can seep in and rot the wood.)

You can to it; just takes a lot of time and money if you want something that will last.