There are basically two ways of doing it (well, actually hundreds, but let's not get into that!
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1. you can go the traditional route and have one (or maybe two) main path running through your plot with beds either side. These are then filled with rows of whatever you're growing, and you leave enough space between the rows to allow walking access to the plants (for cultivation, harvest etc). This is a straightforward method, but does, as mentioned, involve walking on the soil, thus compacting it. If you have heavy clay, this will have greater consequences than on lighter soil. Digging it over in the autumn is the traditional way of countering this.
2. Divide the plot up into individual beds with small permanent access paths in between. Generally these beds tend not to be more than 1.2 metres in width (but that depends on your arm length!), to allow access to the middle from both sides without walking on the soil, and can be any reasonable length. This preserves the soil structure and you don't necessarily need to dig over every autumn (or at all, some say!), and you don't need to keep the traditional spacing between rows to allow access, so whilst you reduce your overall cultivated area (you've sacrificed it to plants), you gain some of that back with the closer planting.
There's endless theory behind both of these. On my plot, I've hedged my bets and divided it up into two - one half goes the traditional route, and the other half is split up into raised beds! I've found that the raised beds are more suited to growing some things (e.g. carrots - I can change the soil structure in a manageable way with extra sand etc to allow me to grow carrots in my otherwise heavy clay), whilst the broad traditional beds are better for others (e.g. large swathes of potatoes or brassicas, which take up loads of room).
The choices are endless, but you can have a lot of fun planning - invest in a pad of graph paper and play around!
Good luck...